Synchronizing your internal clocks may help mitigate jet lag, effects of aging

A hearty breakfast instead of a midnight snack could lead to better sleep when traveling

September 5, 2023

Science Daily/American Institute of Physics

Traveling to faraway places is a great way to seek out new experiences, but jet lag can be an unpleasant side effect. Adjusting to a new time zone is often accompanied by fatigue, difficulty sleeping, and a host of other problems that can turn an otherwise exciting adventure into a miserable trip.

Jet lag is caused by a difference between the circadian system -- the body's internal clock -- and the surrounding environment. Around the turn of the century, scientists began to recognize that the body has multiple internal clocks, calibrated in different ways, and that jet lag-like symptoms can result when these clocks drift out of sync with each other. This can happen in several ways and grows more prevalent with age.

In Chaos, from AIP Publishing, a team of scientists from Northwestern University and the Santa Fe Institute developed a theoretical model to study the interactions between multiple internal clocks under the effects of aging and disruptions like jet lag.

Modern research has shown that circadian clocks are present in almost every cell and tissue in the body. Each relies on its own set of cues to calibrate; the brain's clock depends on sunlight, for instance, while the peripheral organs calibrate at mealtime.

"Conflicting signals, such as warm weather during a short photoperiod or nighttime eating -- eating when your brain is about to rest -- can confuse internal clocks and cause desynchrony," said author Yitong Huang.

At this point, little is known about how the body's various internal clocks affect each other. The added complexity of accounting for multiple clocks means researchers tend to use simplified models.

"Most studies primarily focus on one particular time cue or a single clock," said Huang. "Important gaps remain in our understanding of the synchronization of multiple clocks under conflicting time cues."

Huang and her colleagues took a different approach, building a mathematical framework that accounts for this complex interplay between systems. Their model features two populations of coupled oscillators that mimic the natural rhythms of circadian cycles. Each oscillator influences the others while simultaneously adjusting based on unique external cues.

Using this model, the team was able to explore how such a coupled system could be disrupted and what makes the effect worse. They found that common symptoms of aging, such as weaker signals between circadian clocks and a lower sensitivity to light, result in a system that is more vulnerable to disruptions and slower to recover.

They also landed on a new method to speed up recovery from jet lag and similar disruptions. According to their results, the way to better sleep is through the stomach.

"Having a larger meal in the early morning of the new time zone can help overcome jet lag," says Huang. "Constantly shifting meal schedules or having a meal at night is discouraged, as it can lead to misalignment between internal clocks."

The authors plan to investigate the other side of the equation and identify the factors that result in more resilient internal clocks. Such discoveries could result in recommendations to prevent jet lag in the first place, or to keep the circadian system healthy into old age.

https://www.sciencedaily.com/releases/2023/09/230905124904.htm

A new breakthrough in obesity research may allow you to lose fat while eating all you want

Researchers discover that astrocytes control a cluster of neurons in the brain that regulates energy expenditure

August 31, 2023

Science Daily/Institute for Basic Science

This is a significant development that brings hope to the one billion individuals with obesity worldwide. Researchers led by Director C. Justin LEE from the Center for Cognition and Sociality (CCS) within the Institute for Basic Science (IBS) have discovered new insights into the regulation of fat metabolism. The focus of their study lies within the star-shaped non-neuronal cells in the brain, known as 'astrocytes'. Furthermore, the group announced successful animal experiments using the newly developed drug 'KDS2010', which allowed the mice to successfully achieve weight loss without resorting to dietary restrictions.

The complex balance between food intake and energy expenditure is overseen by the hypothalamus in the brain. While it has been known that the neurons in the lateral hypothalamus are connected to fat tissue and are involved in fat metabolism, their exact role in fat metabolism regulation has remained a mystery. The researchers discovered a cluster of neurons in the hypothalamus that specifically express the receptor for the inhibitory neurotransmitter 'GABA (Gamma-Aminobutyric Acid)'. This cluster has been found to be associated with the α5 subunit of the GABAA receptor and was hence named the GABRA5 cluster.

In a diet-induced obese mouse model, the researchers observed significant slowing in the pacemaker firing of the GABRA5 neurons. Researchers continued with the study by attempting to inhibit the activity of these GABRA5 neurons using chemogenetic methods. This in turn caused a reduction in heat production (energy consumption) in the brown fat tissue, leading to fat accumulation and weight gain. On the other hand, when the GABRA5 neurons in the hypothalamus were activated, the mice were able to achieve a successful weight reduction. This suggests that the GABRA5 neurons may act as a switch for weight regulation.

In a new surprising and unexpected turn of events, the research team discovered that the astrocytes in the lateral hypothalamus regulate the activity of the GABRA5 neurons. The numbers and sizes of the reactive astrocytes are increased, and they begin to overexpress the MAO-B enzyme (Monoamine Oxidase B). This enzyme plays a crucial role in the metabolism of neurotransmitters in the nervous system and is more predominantly expressed in reactive astrocytes. This ends up in the production of a large amount of tonic GABA (Gamma-Aminobutyric Acid), which inhibits the surrounding GABRA5 neurons.

It was also discovered that suppressing the expression of the MAO-B gene in reactive astrocytes can decrease GABA secretion, thereby reversing the undesirable inhibition of the GABRA5 neurons. Using this approach the researchers were able to increase the heat production in the fat tissue of the obese mice, which allowed them to achieve weight loss even while consuming a high-calorie diet. This experimentally proves that the MAO-B enzyme in reactive astrocytes can be an effective target for obesity treatment without compromising appetite.

Furthermore, a selective and reversible MAO-B inhibitor, 'KDS2010', which was transferred to a biotech company Neurobiogen in 2019 and is currently undergoing Phase 1 clinical trials, was tested on an obese mouse model. The new drugs yielded remarkable results, demonstrating a substantial reduction in fat accumulation and weight without any impacts on the amount of food intake.

Postdoctoral researcher SA Moonsun said, "Previous obesity treatments targeting the hypothalamus mainly focused on neuronal mechanisms related to appetite regulation." She added, "To overcome this, we focused on the non-neuronal 'astrocytes' and identified that reactive astrocytes are the cause of obesity."

Center Director C. Justin LEE also said, "Given that obesity has been designated by the World Health Organization (WHO) as the '21st-century emerging infectious disease,' we look to KDS2010 as a potential next-generation obesity treatment that can effectively combat obesity without suppressing appetite."

https://www.sciencedaily.com/releases/2023/08/230831121624.htm

Researchers identify the link between memory and appetite in the human brain to explain obesity

August 30, 2023

Science Daily/University of Pennsylvania School of Medicine

Disrupted connections between memory and appetite regulating brain circuits are directly proportional to body mass index (BMI), notably in patients who suffer from disordered or overeating that can lead to obesity, such as binge eating disorder (BED), according to new research from the Perelman School of Medicine at the University of Pennsylvania. Published today in Nature, the research notes that individuals who are obese have impaired connections between the dorsolateral hippocampus (dlHPC) and the lateral hypothalamus (LH), which may impact their ability to control or regulate emotional responses when anticipating rewarding meals or treats.

"These findings underscore that some individual's brains can be fundamentally different in regions that increase the risk for obesity," senior author, Casey Halpern, MD, an associate professor of Neurosurgery and Chief of Stereotactic and Functional Neurosurgery at Penn Medicine and the Corporal Michael J. Crescenz Veterans Affairs Medical Center. "Conditions like disordered eating and obesity are a lot more complicated than simply managing self-control and eating healthier. What these individuals need is not more willpower, but the therapeutic equivalent of an electrician that can make right these connections inside their brain."

The dlHPC is located in the region of the brain that processes memory, and the LH is in the region of the brain that is responsible for keeping the body in a stable state, called homeostasis. Previous research has found an association with loss of function in the human hippocampus in individuals with obesity and related disordered eating, like BED. However, outside of imaging techniques such as magnetic resonance imaging (MRI), the role of the hippocampus has been difficult to study in humans with obesity and related eating disorders.

In this study, researchers were able to evaluate patients whose brains were already being monitored electrically in the Epilepsy Monitoring Unit. Researchers monitored brain activity as patients anticipated and then received a sweet treat (a chocolate milkshake). They found that both the dlHPC and the LH activated simultaneously when participants anticipated receiving the rewarding meal. These researchers confirmed using stimulation techniques pioneered by coauthors, Kai Miller, MD, PhD, and Dora Hermes Miller, PhD, from Mayo Clinic, that this specific zone of the hippocampus, the dlHPC, and LH exhibited extremely strong connectivity, as well.

In individuals with obesity, researchers found that the impairment of this hypothalamus-hippocampus circuit was directly proportional to their BMI. That is, in participants with a high BMI, the connection was even more disturbed.

To further validate the connection, Halpern's team used a technique called "brain clearing," to analyze brain tissue. The technique revealed melanin-concentrating hormone, a hormone known to regulate feeding behavior that is produced in the LH. They found the presence of MCH in the dlHPC, and nowhere else, confirming a link between the two regions.

"The hippocampus has never been targeted to treat obesity, or the disordered eating that can sometimes cause obesity," said Halpern. "We hope to be able to use this research to both identify which individuals who are likely to develop obesity later in life, and to develop novel therapies -- both invasive and not -- to help improve function of this critical circuit that seems to go awry in patients who are obese."

https://www.sciencedaily.com/releases/2023/08/230830131943.htm

Intermittent fasting improves Alzheimer's pathology

Mice on a time-restricted feeding schedule had better memory and less accumulation of amyloid proteins in the brain compared to controls

August 21, 2023

Science Daily/University of California - San Diego

One of the hallmarks of Alzheimer's disease is disruption to the body's circadian rhythm, the internal biological clock that regulates many of our physiological processes. Nearly 80% of people with Alzheimer's experience these issues, including difficulty sleeping and worsening cognitive function at night. However, there are no existing treatments for Alzheimer's that target this aspect of the disease.

A new study from researchers at University of California San Diego School of Medicine has shown in mice that it is possible to correct the circadian disruptions seen in Alzheimer's disease with time-restricted feeding, a type of intermittent fasting focused on limiting the daily eating window without limiting the amount of food consumed.

In the study, published August 21, 2023 in Cell Metabolism, mice that were fed on a time-restricted schedule showed improvements in memory and reduced accumulation of amyloid proteins in the brain. The authors say the findings will likely result in a human clinical trial.

"For many years, we assumed that the circadian disruptions seen in people with Alzheimer's are a result of neurodegeneration, but we're now learning it may be the other way around -- circadian disruption may be one of the main drivers of Alzheimer's pathology," said senior study author Paula Desplats, PhD, professor in the Department of Neurosciences at UC San Diego School of Medicine. "This makes circadian disruptions a promising target for new Alzheimer's treatments, and our findings provide the proof-of-concept for an easy and accessible way to correct these disruptions."

Alzheimer's disease affects more than 6 million Americans, and it is considered by many to be the biggest forthcoming health challenge in the United States. People with Alzheimer's experience a variety of disruptions to their circadian rhythms, including changes to their sleep/wake cycle, increased cognitive impairment and confusion in the evenings, and difficulty falling and staying asleep.

"Circadian disruptions in Alzheimer's are the leading cause of nursing home placement," said Desplats. "Anything we can do to help patients restore their circadian rhythm will make a huge difference in how we manage Alzheimer's in the clinic and how caregivers help patients manage the disease at home."

Boosting the circadian clock is an emerging approach to improving health outcomes, and one way to accomplish this is by controlling the daily cycle of feeding and fasting. The researchers tested this strategy in a mouse model of Alzheimer's disease, feeding the mice on a time-restricted schedule where they were only allowed to eat within a six-hour window each day. For humans, this would translate to about 14 hours of fasting each day.

Compared to control mice who were provided food at all hours, mice fed on the time-restricted schedule had better memory, were less hyperactive at night, followed a more regular sleep schedule and experienced fewer disruptions during sleep. The test mice also performed better on cognitive assessments than control mice, demonstrating that the time-restricted feeding schedule was able to help mitigate the behavioral symptoms of Alzheimer's disease.

The researchers also observed improvements in the mice on a molecular level. In mice fed on a restricted schedule, the researchers found that multiple genes associated with Alzheimer's and neuroinflammation were expressed differently. They also found that the feeding schedule helped reduce the amount of amyloid protein that accumulated in the brain. Amyloid deposits are one of the most well-known features of Alzheimer's disease.

Because the time-restricted feeding schedule was able to substantially change the course of Alzheimer's in the mice, the researchers are optimistic that the findings could be easily translatable to the clinic, especially since the new treatment approach relies on a lifestyle change rather than a drug.

"Time-restricted feeding is a strategy that people can easily and immediately integrate into their lives," said Desplats. "If we can reproduce our results in humans, this approach could be a simple way to dramatically improve the lives of people living with Alzheimer's and those who care for them."

https://www.sciencedaily.com/releases/2023/08/230821153213.htm

Adherence to a Mediterranean lifestyle associated with lower risk of all-cause and cancer mortality

August 16, 2023

Science Daily/Harvard T.H. Chan School of Public Health

People who adhere to a Mediterranean lifestyle -- which includes a diet rich in fruits, vegetables, and whole grains; healthy eating habits like limiting added salts and sugars; and habits promoting adequate rest, physical activity, and socialization -- have a lower risk of all-cause and cancer mortality, according to a new study led by La Universidad Autónoma de Madrid and Harvard T.H. Chan School of Public Health. People who adhered to the lifestyle's emphasis on rest, exercise, and socializing with friends had a lower risk of cardiovascular disease mortality.

The study will be published on Wednesday, August 16, in Mayo Clinic Proceedings.

While many studies have established the health benefits of a Mediterranean diet and lifestyle, little research has been conducted on the diet outside of its region of origin. "This study suggests that it's possible for non-Mediterranean populations to adopt the Mediterranean diet using locally available products and to adopt the overall Mediterranean lifestyle within their own cultural contexts," said lead author Mercedes Sotos Prieto, Ramon y Cajal research fellow at La Universidad Autónoma de Madrid and adjunct assistant professor of environmental health at Harvard Chan School. "We're seeing the transferability of the lifestyle and its positive effects on health."

The researchers analyzed the habits of 110,799 members of the UK Biobank cohort, a population-based study across England, Wales, and Scotland using the Mediterranean Lifestyle (MEDLIFE) index, which is derived from a lifestyle questionnaire and diet assessments. Participants, who were between the ages of 40 and 75, provided information about their lifestyle according to the three categories the index measures: "Mediterranean food consumption" (intake of foods part of the Mediterranean diet such as fruits and whole grains); "Mediterranean dietary habits" (adherence to habits and practices around meals, including limiting salt and drinking healthy beverages); and "physical activity, rest, and social habits and conviviality" (adherence to lifestyle habits including taking regular naps, exercising, and spending time with friends). Each item within the three categories was then scored, with higher total scores indicating higher adherence to the Mediterranean lifestyle.

The researchers followed up nine years later to examine participants' health outcomes. Among the study population, 4,247 died from all causes; 2,401 from cancer; and 731 from cardiovascular disease. Analyzing these results alongside MEDLIFE scores, the researchers observed an inverse association between adherence to the Mediterranean lifestyle and risk of mortality. Participants with higher MEDLIFE scores were found to have a 29% lower risk of all-cause mortality and a 28% lower risk of cancer mortality compared to those with lower MEDLIFE scores. Adherence to each MEDLIFE category independently was associated with lower all-cause and cancer mortality risk. The "physical activity, rest, and social habits and conviviality" category was most strongly associated with these lowered risks, and additionally was associated with a lower risk of cardiovascular disease mortality.

https://www.sciencedaily.com/releases/2023/08/230816170623.htm

How cold temperatures trigger the brain to boost appetite

August 16, 2023

Science Daily/Scripps Research Institute

Neuroscientists at Scripps Research have identified brain circuits that make mammals want to eat more when they are exposed to cold temperatures.

Mammals automatically burn more energy to maintain normal body temperature when exposed to cold. This cold-activated increase in energy expenditure triggers an increase in appetite and feeding, although the specific mechanism controlling this had been unknown. In the new study, reported on August 16, 2023, in Nature, the researchers identified a cluster of neurons that work as a "switch" for this cold-related, food-seeking behavior in mice. The discovery could lead to potential therapeutics for metabolic health and weight loss.

"This is a fundamental adaptive mechanism in mammals and targeting it with future treatments might allow the enhancement of the metabolic benefits of cold or other forms of fat burning," says study senior author Li Ye, PhD, associate professor and the Abide-Vividion Chair in Chemistry and Chemical Biology at Scripps Research.

The study's first author was Ye Lab postdoctoral research associate Neeraj Lal, PhD.

Because exposure to cold leads to enhanced energy burning to stay warm, cold water immersion and other forms of "cold therapy" have been explored as methods for losing weight and improving metabolic health. One drawback of cold therapies is that humans' evolved responses to cold are not designed to cause weight loss (an effect that could have been fatal during the frequent periods of food scarcity in pre-modern times). Cold, like dieting and exercise, increases appetite to counteract any weight-loss effect. In the study, Ye and his team set out to identify the brain circuitry that mediates this cold-induced appetite increase.

One of their first observations was that, with the onset of cold temperatures (from 73F to 39F), mice increase their food seeking only after a delay of about six hours, suggesting this behavioral change is not simply a direct result of cold sensing.

Using techniques called whole-brain clearing and light sheet microscopy, the researchers compared the activity of neurons across the brain during cold versus warm conditions. Soon they made a key observation: While most of the neuronal activity across the brain was much lower in the cold condition, portions of a region called the thalamus showed higher activation.

Eventually, the team zeroed in on a specific cluster of neurons called the xiphoid nucleus of the midline thalamus, showing that activity in these neurons spiked under cold conditions just before the mice stirred from their cold-induced torpor to look for food. When less food was available at the onset of the cold condition, the activity increase in the xiphoid nucleus was even greater -- suggesting that these neurons respond to a cold-induced energy deficit rather than cold itself.

When the researchers artificially activated these neurons, the mice increased their food-seeking, but not other activities. Similarly, when the team inhibited the activity of these neurons, the mice decreased their food-seeking. These effects appeared only under the cold condition, implying that cold temperatures provide a separate signal that must also be present for appetite changes to occur.

In a last set of experiments, the team showed that these xiphoid nucleus neurons project to a brain region called the nucleus accumbens -- an area long known for its role in integrating reward and aversion signals to guide behavior, including feeding behavior.

Ultimately, these results may have clinical relevance, Ye says, for they suggest the possibility of blocking the usual cold-induced appetite increase, allowing relatively simple cold exposure regimens to drive weight loss much more efficiently.

"One of our key goals now is to figure out how to decouple the appetite increase from the energy-expenditure increase," he says. "We also want to find out if this cold-induced appetite-increase mechanism is part of a broader mechanism the body uses to compensate for extra energy expenditure, for example after exercise."

https://www.sciencedaily.com/releases/2023/08/230816114222.htm

Brain's 'appetite control center' different in people who are overweight or living with obesity

August 8, 2023

Science Daily/University of Cambridge

Cambridge scientists have shown that the hypothalamus, a key region of the brain involved in controlling appetite, is different in the brains of people who are overweight and people with obesity when compared to people who are a healthy weight.

Cambridge scientists have shown that the hypothalamus, a key region of the brain involved in controlling appetite, is different in the brains of people who are overweight and people with obesity when compared to people who are a healthy weight.

The researchers say their findings add further evidence to the relevance of brain structure to weight and food consumption.

Current estimations suggest that over 1.9 billion people worldwide are either overweight or obese. In the UK, according to the Office for Health Improvement & Disparities, almost two-thirds of adults are overweight or living with obesity. This increases an individual's risk of developing a number of health problems, including type 2 diabetes, heart disease and stroke, cancer and poorer mental health.

A large number of factors influence how much we eat and the types of food we eat, including our genetics, hormone regulation, and the environment in which we live. What happens in our brains to tell us that we are hungry or full is not entirely clear, though studies have shown that the hypothalamus, a small region of the brain about the size of an almond, plays an important role.

Dr Stephanie Brown from the Department of Psychiatry and Lucy Cavendish College, University of Cambridge, said: "Although we know the hypothalamus is important for determining how much we eat, we actually have very little direct information about this brain region in living humans. That's because it is very small and hard to make out on traditional MRI brain scans."

The majority of evidence for the role of the hypothalamus in appetite regulation comes from animal studies. These show that there are complex interacting pathways within the hypothalamus, with different cell populations acting together to tell us when we are hungry or full.

To get around this, Dr Brown and colleagues used an algorithm developed using machine learning to analyse MRI brain scans taken from 1,351 young adults across a range of BMI scores, looking for differences in the hypothalamus when comparing individuals who are underweight, healthy weight, overweight and living with obesity.

In a study published today in Neuroimage: Clinical, the team found that the overall volume of the hypothalamus was significantly larger in the overweight and obese groups of young adults. In fact, the team found a significant relationship between volume of the hypothalamus and body-mass index (BMI).

These volume differences were most apparent in those sub-regions of the hypothalamus that control appetite through the release of hormones to balance hunger and fullness.

While the precise significance of the finding is unclear -- including whether the structural changes are a cause or a consequence of the changes in body weight -- one possibility is that the change relates to inflammation. Previous animal studies have shown that a high fat diet can cause inflammation of the hypothalamus, which in turn prompts insulin resistance and obesity. In mice, just three days of a fat-rich diet is enough to cause this inflammation. Other studies have shown that this inflammation can raise the threshold at which animals are full -- in other words, they have to eat more food than usual to feel full.

Dr Brown, the study's first author, added: "If what we see in mice is the case in people, then eating a high-fat diet could trigger inflammation of our appetite control centre. Over time, this would change our ability to tell when we've eaten enough and to how our body processes blood sugar, leading us to put on weight."

Inflammation may explain why the hypothalamus is larger in these individuals, the team say. One suggestion is that the body reacts to inflammation by increasing the size of the brain's specialist immune cells, known as glia.

Professor Paul Fletcher, the study's senior author, from the Department of Psychiatry and Clare College, Cambridge, said: "The last two decades have given us important insights about appetite control and how it may be altered in obesity. Metabolic researchers at Cambridge have played a leading role in this.

"Our hope is that by taking this new approach to analysing brain scans in large datasets, we can further extend this work into humans, ultimately relating these subtle structural brain findings to changes in appetite and eating and generating a more comprehensive understanding of obesity."

The team say more research is needed to confirm whether increased volume in the hypothalamus is a result of being overweight or whether people with larger hypothalami are predisposed to eat more in the first place. It is also possible that these two factors interact with each other causing a feedback loop.

https://www.sciencedaily.com/releases/2023/08/230808110931.htm

Fewer teens now perceive themselves as overweight -- international study of more than 745,000 adolescents

Changes in body weight perception could undermine public health interventions to tackle obesity

July 4, 2023

Science Daily/Taylor & Francis Group

A study involving more than 745,000 adolescents from 41 countries across Europe and North America identified an increase in the amount of teenagers who underestimate their body weight.

Tracking data from 2002 to 2018, the peer-reviewed findings, published today in Child and Adolescent Obesity, demonstrate a noticeable decrease in those who overestimate their weight too.

The team of international experts, who carried out the research, warn these shifting trends in body weight perception could reduce the effectiveness of public health interventions aimed at weight reduction in young people.

"During this impressionable age, body weight perception may influence a young person's lifestyle choices, such as the amount and types of food they eat and their exercise habits," says lead author Doctor Anouk Geraets, from the Department of Social Sciences, at the University of Luxembourg.

"So it's concerning that we're seeing a trend where fewer adolescents perceive themselves as being overweight -- as this could undermine ongoing efforts to tackle increasing levels of obesity in this age group. Young people who underestimate their weight and therefore do not consider themselves to be overweight may not feel they need to lose excess weight and, as a result, they may make unhealthy lifestyle choices."

A person's perception of their body weight may not accurately reflect their actual weight. A discrepancy in body weight perception (BWP) may either be an underestimation (where actual weight is higher than perceived weight) or an overestimation (where actual weight is lower than perceived weight).

In the present study, the researchers examined survey data from 746,121 11-, 13- and 15-year-olds from 41 countries collected at four-yearly intervals between 2002 and 2018 in the International Health Behavior in School-Aged Children (HBSC), a WHO collaborative study.

The team modeled trends in BWP among adolescents across different countries over time, making adjustments for age, gender, and family socioeconomic status. They found:

• Underestimation of weight status increased, and overestimation of weight status decreased over time among both sexes, with stronger trends for girls.

• Correct weight perception increased over time among girls, while it decreased among boys.

• Changes in correct weight perception, underestimation and overestimation of weight status differed across different countries -- but these changes could not be explained by an increase in country-level overweight/obesity prevalence.

The authors speculated that the observed differences between girls and boys in BWP may support the idea there are sex differences in body ideals -- and that these body ideals have changed over time. Notably, the increased underestimation and decreased overestimation of weight status over time for girls may be explained by the emergence of an athletic and strong body, as a new contemporary body ideal for both sexes.

"This study has clinical and public health implications. The increase in correct weight perception and the decrease in overestimation may have a positive effect on unnecessary and unhealthy weight loss behaviors among adolescents, while the increase in underestimation might indicate the need for interventions to strengthen correct weight perception," says lead author Doctor Anouk Geraets.

"More research is now needed to understand the factors underlying these time trends and to develop effective public health interventions."

While the large number of participating countries is a strength of the present study -- but as these only included countries in Europe, the USA and Canada, the results can't be generalized to other regions. In addition, although steps were taken to adjust the models for certain potential confounding factors, several other factors -- such as body image, dieting, changing eating patterns, or migration -- may also have played a role in the observed trends over time.

https://www.sciencedaily.com/releases/2023/07/230704110936.htm

Fasting can help you lose weight, but you might gain it back quickly

June 29, 2023

Science Daily/University of Illinois Chicago

Water fasts -- where people consume nothing but water for several days -- might help you lose weight, but it's unclear how long you'll keep it off, according to research from the University of Illinois Chicago. And the other metabolic benefits of water fasts, such as lower blood pressure and improved cholesterol, seem to disappear soon after the fast ends, the researchers found.

However, there do not appear to be any serious adverse effects for those who do a water fast or a similar kind of fast where people consume a very small number of calories a day, said Krista Varady, professor of kinesiology and nutrition, who led the research, which is published in Nutrition Reviews.

"My overall conclusion is that I guess you could try it, but it just seems like a lot of work, and all those metabolic benefits disappear," Varady said. She stressed, however, that no one should undertake one of these fasts for more than five days without medical supervision.

Varady, an expert on intermittent fasting, said she wanted to study water fasting because she suddenly started getting contacted by journalists last fall who wanted to hear what she thought about it. She figured if she was going to comment, she should investigate the existing research.

The new paper is a literature review of eight studies on water fasting or Buchinger fasting, a medically supervised fast that is popular in Europe where people consume only a tiny amount of juice and soup a day. Varady's team looked at the results from each of those papers to see what story they cumulatively tell about the fasts' impact on weight loss, as well as a number of other metabolic factors.

Fasting did seem to spur noticeable short-term weight loss, the researchers found. People who fasted for five days lost about 4% to 6% of their weight; those who fasted for seven to 10 days lost about 2% to 10%, and those who fasted for 15 to 20 days lost 7% to 10%.

Only a few of the studies in the review tracked whether participants gained back the weight they had lost once the fast ended. In one of those, people gained back all they had lost in a five-day water fast within three months. In two other studies, only a small amount of the lost weight returned, but those studies encouraged participants to restrict their calorie intake after the fasts ended.

In contrast, it was clear that the metabolic benefits of the fasts disappeared soon after the fasts ended. Improvements to blood pressure, cholesterol and blood sugar levels were short-lived, returning to baseline levels quickly after participants started eating again.

Some of the studies included participants with Type 1 and Type 2 diabetes, who suffered no ill effects from the fasting, though they were monitored closely and had their insulin doses adjusted while fasting.

The most common side effects of these prolonged fasts were similar to those from intermittent fasting, Varady said, such as headaches, insomnia and hunger. There were no serious negative effects in the studies, such as metabolic acidosis or death.

She did note that the participants in these prolonged fasts lost about two-thirds of their weight in lean mass and one-third in fat mass. This is the opposite of what happens most of the time during weight loss, where more fat is lost than muscle. It makes sense that these extreme fasts would have this result, she said, because "your body needs a constant intake of protein. If it doesn't have that, then it draws from muscles."

Varady's research into intermittent fasting has looked at how well the regime works for weight loss, as well as at specific questions, such as whether intermittent fasting affects fertility -- she found it does not.

Varady said she would encourage someone hoping to lose weight to try intermittent fasting instead of a water fast, "because there's a lot more data to show it can help with weight management," she said.

https://www.sciencedaily.com/releases/2023/06/230629125656.htm

Colorful fresh foods improve athletes' vision

Visual range is a critical asset for top athletes in almost any sport

June 8, 2023

Science Daily/University of Georgia

Nutrition is an important part of any top athlete's training program. And now, a new study by researchers from the University of Georgia proposes that supplementing the diet of athletes with colorful fruits and vegetables could improve their visual range.

The paper, which was published in Exercise and Sport Sciences Reviews, examines how a group of plant compounds that build up in the retina, known as macular pigments, work to improve eye health and functional vision.

Previous studies done by UGA researchers Billy R. Hammond and Lisa Renzi-Hammond have shown that eating foods like dark leafy greens or yellow and orange vegetables, which contain high levels of the plant compounds lutein and zeaxanthin, improves eye and brain health.

"A lot of the research into macular lutein and zeaxanthin has focused on health benefits, but from a functional perspective, higher concentrations of these plant pigments improve many aspects of visual and cognitive ability. In this paper, we discuss their ability to improve vision in the far distance or visual range," said lead author Jack Harth, a doctoral candidate in UGA's College of Public Health.

Visual range, or how well a person can see a target clearly over distance, is a critical asset for top athletes in almost any sport.

The reason why objects get harder to see and appear fuzzier the farther they are from our eyes is thanks in part to the effects of blue light.

"From a center fielder's perspective, if that ball's coming up in the air, it will be seen against a background of bright blue sky, or against a gray background if it's a cloudy day. Either way, the target is obscured by atmospheric interference coming into that path of the light," said Harth.

Many athletes already take measures to reduce the impact of blue light through eye black or blue blocker sunglasses, but eating more foods rich in lutein and zeaxanthin can improve the eye's natural ability to handle blue light exposure, said Harth.

When a person absorbs lutein and zeaxanthin, the compounds collect as yellow pigments in the retina and act as a filter to prevent blue light from entering the eye.

Previous work had been done testing the visual range ability of pilots in the 1980s, and Hammond and Renzi-Hammond have done more recent studies on how macular pigment density, or how much yellow pigment is built up in the retina, is linked to a number of measures of eye health and functional vision tests.

"In a long series of studies, we have shown that increasing amounts of lutein and zeaxanthin in the retina and brain decrease glare disability and discomfort and improve chromatic contrast and visual-motor reaction time, and supplementing these compounds facilitates executive functions like problem-solving and memory. All of these tasks are particularly important for athletes," said corresponding author Billy R. Hammond, a professor of psychology in the Behavior and Brain Sciences Program at UGA's Franklin College of Arts and Sciences.

This paper, Harth said, brings the research on these links between macular pigment and functional vision up to date and asks what the evidence suggests about optimizing athletic performance.

"We're at a point where we can say we've seen visual range differences in pilots that match the differences found in modeling, and now, we've also seen it in laboratory tests, and a future goal would be to actually bring people outside and to measure their ability to see contrast over distance through real blue haze and in outdoor environments," said Harth.

But before you start chowing down on kale in the hopes of improving your game, he cautions that everybody is different. That could mean the way our bodies absorb and use lutein and zeaxanthin varies, and it could take a while before you notice any improvements, if at all.

Still, the evidence of the overall health benefits of consuming more lutein and zeaxanthin are reason enough to add more color to your diet, say the authors.

"We have data from modeling and empirical studies showing that higher macular pigment in your retina will improve your ability to see over distance. The application for athletes is clear," said Harth.

https://www.sciencedaily.com/releases/2023/06/230608120930.htm

How chronic stress drives the brain to crave comfort food

June 8, 2023

Science Daily/Garvan Institute of Medical Research

Stress can override natural satiety cues to drive more food intake and boost cravings for sweets.

When you're stressed, a high-calorie snack may seem like a comforting go-to. But this combination has an unhealthy downside. According to Sydney scientists, stress combined with calorie-dense 'comfort' food creates changes in the brain that drive more eating, boost cravings for sweet, highly palatable food and lead to excess weight gain.

A team from the Garvan Institute of Medical Research found that stress overrode the brain's natural response to satiety, leading to non-stop reward signals that promote eating more highly palatable food. This occurred in a part of the brain called the lateral habenula, which when activated usually dampens these reward signals.

"Our findings reveal stress can override a natural brain response that diminishes the pleasure gained from eating -- meaning the brain is continuously rewarded to eat," says Professor Herzog, senior author of the study and Visiting Scientist at the Garvan Institute.

"We showed that chronic stress, combined with a high-calorie diet, can drive more and more food intake as well as a preference for sweet, highly palatable food, thereby promoting weight gain and obesity. This research highlights how crucial a healthy diet is during times of stress."

The research was published in the journal Neuron.

From stressed brain to weight gain

While some people eat less during times of stress, most will eat more than usual and choose calorie-rich options high in sugar and fat.

To understand what drives these eating habits, the team investigated in mouse models how different areas in the brain responded to chronic stress under various diets.

"We discovered that an area known as the lateral habenula, which is normally involved in switching off the brain's reward response, was active in mice on a short-term, high-fat diet to protect the animal from overeating. However, when mice were chronically stressed, this part of the brain remained silent -- allowing the reward signals to stay active and encourage feeding for pleasure, no longer responding to satiety regulatory signals," explains first author Dr Kenny Chi Kin Ip from the Garvan Institute.

"We found that stressed mice on a high-fat diet gained twice as much weight as mice on the same diet that were not stressed."

The researchers discovered that at the centre of the weight gain was the molecule NPY, which the brain produces naturally in response to stress. When the researchers blocked NPY from activating brain cells in the lateral habenula in stressed mice on a high-fat diet, the mice consumed less comfort food, resulting in less weight gain.

Driving comfort eating

The researchers next performed a 'sucralose preference test' -- allowing mice to choose to drink either water or water that had been artificially sweetened.

"Stressed mice on a high-fat diet consumed three times more sucralose than mice that were on a high-fat diet alone, suggesting that stress not only activates more reward when eating but specifically drives a craving for sweet, palatable food," says Professor Herzog.

"Crucially, we did not see this preference for sweetened water in stressed mice that were on a regular diet."

Stress overrides healthy energy balance

"In stressful situations it's easy to use a lot of energy and the feeling of reward can calm you down -- this is when a boost of energy through food is useful. But when experienced over long periods of time, stress appears to change the equation, driving eating that is bad for the body long term," says Professor Herzog.

The researchers say their findings identify stress as a critical regulator of eating habits that can override the brain's natural ability to balance energy needs.

"This research emphasises just how much stress can compromise a healthy energy metabolism," says Professor Herzog. "It's a reminder to avoid a stressful lifestyle, and crucially -- if you are dealing with long-term stress -- try to eat a healthy diet and lock away the junk food."

https://www.sciencedaily.com/releases/2023/06/230608120905.htm

Obesity increases risk of mental disorders throughout life

May 30, 2023

Science Daily/Complexity Science Hub Vienna

Being obese significantly increases the chances of also developing mental disorders. This applies to all age groups, with women at higher risk than men for most diseases, as a recent study of the Complexity Science Hub and the Medical University of Vienna shows. The results were published in the specialist journal Translational Psychiatry.

"We analyzed a population-wide national registry of inpatient hospitalizations in Austria from 1997 to 2014 in order to determine the relative risks of comorbidities in obesity and identify statistically significant sex differences," explains Elma Dervic of the Complexity Science Hub. Consequently, it became evident that an obesity diagnosis significantly enhances the likelihood of a wide range of mental disorders across all age groups -- including depression, nicotine addiction, psychosis, anxiety, eating and personality disorders. "From a clinical point of view, these results emphasise the need to raise awareness of psychiatric diagnoses in obese patients and, if necessary, to consult specialists at an early stage of diagnosis," says Michael Leutner of the Medical University of Vienna.

FIRST DIAGNOSIS: OBESITY

"In order to find out which illness typically appeared prior and subsequently to the obesity diagnosis, we had to develop a new method," explains Dervic. This allowed the researchers to determine if there were trends and typical patterns in disease occurrence.

In case of all co-diagnoses, with the exception of the psychosis spectrum, obesity was in all likelihood the first diagnosis made prior to the manifestation of a psychiatric diagnosis. "Until now, physicians often considered psychopharmacological medications to cause the association between mental disorders and obesity as well as diabetes. This may be true for schizophrenia, where we see the opposite time order, but our data does not support this for depression or other psychiatric diagnoses," explains Alexander Kautzky from Department of Psychiatry and Psychotherapy of the Medical University Vienna. However, whether obesity directly affects mental health or whether early stages of psychiatric disorders are inadequately recognised is not yet known.

GREATER IMPACT IN WOMEN

Surprisingly, the researchers found significant gender differences for most disorders -- with women showing an increased risk for all disorders except schizophrenia and nicotine addiction.

While 16.66% of obese men also suffer from nicotine abuse disorder, this is only the case in up to 8.58% of obese women. The opposite is true for depression. The rate of diagnosed depressive episodes was almost three times higher in obese women (13.3% obese; 4.8% non-obese). Obese men were twice as likely to be affected (6.61% obese; 3.21% non-obese).

COUNTERACT AT A YOUNG AGE

At present, obesity is a highly prevalent disease worldwide and affects more than 670 million people. The fact that the disease promotes metabolic disorders and serious cardio-metabolic complications (diabetes mellitus, arterial hypertension, and dyslipidaemia) has already been extensively researched.

Since this study now also shows that obesity often precedes severe mental disorders, the findings underscore its importance as a pleiotropic risk factor for health problems of all kinds. This is primarily true for young age groups, where the risk is most pronounced. For this reason, thorough screening for mental health problems in obese patients is urgently needed to facilitate prevention or ensure that appropriate treatment can be given, so the researchers conclude.

https://www.sciencedaily.com/releases/2023/05/230530125412.htm

Junk food may impair our deep sleep

May 30, 2023

Science Daily/Uppsala University

In a new study, researchers at Uppsala University have investigated how junk food affects sleep. Healthy participants consumed an unhealthier as well as a healthier diet in a randomised order. After the unhealthier diet, the quality of the participants' deep sleep had deteriorated, compared with those who had followed the healthier diet. The results have been published in the journal Obesity.

Several epidemiological studies have shown that what we eat is associated with changes in our sleep. However, few studies have investigated how diet itself directly affects sleep. One way to do that is to have the same participant consume different diets in a randomised order.

"Both poor diet and poor sleep increase the risk of several public health conditions. As what we eat is so important for our health, we thought it would be interesting to investigate whether some of the health effects of different diets could involve changes to our sleep. In this context, so-called intervention studies have so far been lacking; studies designed to allow the mechanistic effect of different diets on sleep to be isolated," says Jonathan Cedernaes, Physician and Associate Professor in Medical Cell Biology at Uppsala University.

Previous epidemiological studies have shown that diets with greater sugar content, for example, are linked to poorer sleep. Yet sleep is an interplay of different physiological states, as Cedernaes explains:

"For example, deep sleep can be affected by what we eat. But no study had previously investigated what happens if we consume an unhealthy diet and then compared it to quality of sleep after that same person follows a healthy diet. What is exciting in this context is that sleep is very dynamic. Our sleep consists of different stages with different functions, such as deep sleep which regulates hormonal release, for example. Furthermore, each sleep stage is hallmarked by different types of electrical activity in the brain. This regulates aspects such as how restorative sleep is, and differs across different brain regions. But the depth or integrity of the sleep stages can also be negatively affected by factors such as insomnia and ageing. Previously, it has not been investigated whether similar changes in our sleep stages can occur after exposure to different diets."

Each study session involved several days of monitoring in a sleep laboratory. Therefore, only 15 individuals were included in the study. A total of 15 healthy normal-weight young men participated in two sessions. Participants were first screened for aspects such as their sleep habits, which had to be normal and within the recommended range (an average of seven to nine hours of sleep per night).

In random order, the participants were given both a healthier diet and an unhealthier diet. The two diets contained the same number of calories, adjusted to each individual's daily requirements. Among other things, the unhealthier diet contained a higher content of sugar and saturated fat and more processed food items. The meals of each diet had to be consumed at individually adjusted times, which were matched across the two dietary conditions. Each diet was consumed for a week, while the participants' sleep, activity and meal schedules were monitored at an individual level.

After each diet, the participants were examined in a sleep laboratory. There, they were first allowed to sleep a normal night, while their brain activity was measured to monitor their sleep. The participants were then kept awake in the sleep laboratory, before being allowed to catch up on sleep. Their sleep was recorded in this case, too.

"What we saw was that the participants slept for the same amount of time when they consumed the two diets. This was the case both while they were following the diets, as well as after they had switched to another, identical diet. In addition, across the two diets, the participants spent the same amount of time in the different sleep stages. But we were particularly interested in investigating the properties of their deep sleep. Specifically, we looked at slow-wave activity, a measure that can reflect how restorative deep sleep is. Intriguingly, we saw that deep sleep exhibited less slow-wave activity when the participants had eaten junk food, compared with consumption of healthier food. This effect also lasted into a second night, once we had switched the participants to an identical diet. Essentially, the unhealthy diet resulted in shallower deep sleep. Of note, similar changes in sleep occur with ageing and in conditions such as insomnia. It can be hypothesised, from a sleep perspective, that greater importance should potentially be attached to diet in such conditions," explains Cedernaes.

The researchers do not currently know how long-lasting the sleep effects of the unhealthier diet may be. The study did not investigate whether the shallower deep sleep may alter functions that are regulated by deep sleep, for example.

"It would also be interesting to conduct functional tests, for example to see whether memory function can be affected. This is regulated to a large extent by sleep. And it would be equally interesting to understand how long-lasting the observed effects may be. Currently, we do not know which substances in the unhealthier diet worsened the depth of deep sleep. As in our case, unhealthy diets often contain both higher proportions of saturated fat and sugar and a lower proportion of dietary fibre. It would be interesting to investigate whether there is a particular molecular factor that plays a greater role. Our dietary intervention was also quite short, and both the sugar and fat content could have been higher. It is possible that an even unhealthier diet would have had more pronounced effects on sleep," notes Cedernaes.

https://www.sciencedaily.com/releases/2023/05/230530125400.htm

Low-flavanol diet drives age-related memory loss

May 29, 2023

Science Daily/Columbia University Irving Medical Center

Age-related memory loss is likely caused, in part, by lack of flavanols -- nutrients found in certain fruits and vegetables -- according to a large study in older adults.

A large-scale study led by researchers at Columbia and Brigham and Women's Hospital/Harvard is the first to establish that a diet low in flavanols -- nutrients found in certain fruits and vegetables -- drives age-related memory loss.

The study found that flavanol intake among older adults tracks with scores on tests designed to detect memory loss due to normal aging and that replenishing these bioactive dietary components in mildly flavanol-deficient adults over age 60 improves performance on these tests.

"The improvement among study participants with low-flavanol diets was substantial and raises the possibility of using flavanol-rich diets or supplements to improve cognitive function in older adults," says Adam Brickman, PhD, professor of neuropsychology at Columbia University Vagelos College of Physicians and Surgeons and co-leader of the study.

The finding also supports the emerging idea that the aging brain requires specific nutrients for optimal health, just as the developing brain requires specific nutrients for proper development.

"The identification of nutrients critical for the proper development of an infant's nervous system was a crowning achievement of 20th century nutrition science," says the study's senior author, Scott Small, MD, the Boris and Rose Katz Professor of Neurology at Columbia University Vagelos College of Physicians and Surgeons.

"In this century, as we are living longer research is starting to reveal that different nutrients are needed to fortify our aging minds. Our study, which relies on biomarkers of flavanol consumption, can be used as a template by other researchers to identify additional, necessary nutrients."

Age-related memory loss linked to changes in hippocampus

The current study builds on over 15 years of research in Small's lab linking age-related memory loss to changes in the dentate gyrus, a specific area within the brain's hippocampus -- a region that is vital for learning new memories -- and showing that flavanols improved function in this brain region.

Additional research, in mice, found that flavanols -- particularly a bioactive substance in flavanols called epicatechin -- improved memory by enhancing the growth of neurons and blood vessels and in the hippocampus.

Next, Small's team tested flavanol supplements in people. One small study confirmed that the dentate gyrus is linked to cognitive aging. A second, larger trial showed that flavanols improved memory by acting selectively on this brain region and had the most impact on those starting out with a poor-quality diet.

In the new study, the Columbia team collaborated with researchers at Brigham and Women's Hospital studying the effects of flavanols and multivitamins in COSMOS (COcoa Supplements and Multivitamin Outcomes Study). The current study, COSMOS-Web, was designed to test the impact of flavanols in a much larger group and explore whether flavanol deficiency drives cognitive aging in this area of the brain.

Study methods

More than 3,500 healthy older adults were randomly assigned to receive a daily flavanol supplement (in pill form) or placebo pill for three years. The active supplement contained 500 mg of flavanols, including 80 mg epicatechins, an amount that adults are advised to get from food.

At the beginning of the study, all participants completed a survey that assessed the quality of their diet, including foods known to be high in flavanols. Participants then performed a series of web-based activities in their own homes, designed and validated by Brickman, to assess the types of short-term memory governed by the hippocampus. The tests were repeated after years one, two, and three. Most of the participants identified themselves as non-Hispanic and white.

More than a third of the participants also supplied urine samples that allowed researchers to measure a biomarker for dietary flavanol levels, developed by co-study authors at Reading University in the UK, before and during the study. The biomarker gave the researchers a more precise way to determine if flavanol levels corresponded to performance on the cognitive tests and ensure that participants were sticking to their assigned regimen (compliance was high throughout the study). Flavanol levels varied moderately, though no participants were severely flavanol-deficient.

People with mild flavanol deficiency benefited from flavanol supplement

Memory scores improved only slightly for the entire group taking the daily flavanol supplement, most of whom were already eating a healthy diet with plenty of flavanols.

But at the end of the first year of taking the flavanol supplement, participants who reported consuming a poorer diet and had lower baseline levels of flavanols saw their memory scores increase by an average of 10.5% compared to placebo and 16% compared to their memory at baseline. Annual cognitive testing showed the improvement observed at one year was sustained for at least two more years.

The results strongly suggest that flavanol deficiency is a driver of age-related memory loss, the researchers say, because flavanol consumption correlated with memory scores and flavanol supplements improved memory in flavanol-deficient adults.

The findings of the new study are consistent with those of a recent study, which found that flavanol supplements did not improve memory in a group of people with a range of baseline flavanol levels. The previous study did not look at the effects of flavanol supplements on people with low and high flavanol levels separately.

"What both studies show is that flavanols have no effect on people who don't have a flavanol deficiency," Small says.

It's also possible that the memory tests used in the previous study did not assess memory processes in the area of the hippocampus affected by flavanols. In the new study, flavanols only improved memory processes governed by the hippocampus and did not improve memory mediated by other areas of the brain.

Next steps

"We cannot yet definitively conclude that low dietary intake of flavanols alone causes poor memory performance, because we did not conduct the opposite experiment: depleting flavanol in people who are not deficient," Small says, adding that such an experiment might be considered unethical.

The next step needed to confirm flavanols' effect on the brain, Small says, is a clinical trial to restore flavanol levels in adults with severe flavanol deficiency.

"Age-related memory decline is thought to occur sooner or later in nearly everyone, though there is a great amount of variability," says Small. "If some of this variance is partly due to differences in dietary consumption of flavanols, then we would see an even more dramatic improvement in memory in people who replenish dietary flavanols when they're in their 40s and 50s."

https://www.sciencedaily.com/releases/2023/05/230529171757.htm

You can satisfy your appetite just by looking at pictures of food on your phone

The results may lead to a new form of treatment for overeating

May 22, 2023

Science Daily/Aarhus University

The internet is overflowing with pictures of food: On news sites, social media and the banner ads that pop up everywhere.

Many of the food images are uploaded to sell specific foods. The idea is that the images on Facebook or Instagram will make us yearn for a McDonalds burger, for example. In other words, the image awakens our hunger.

New research from Aarhus University now shows that the images can actually have the opposite effect. At least if we see pictures of the same product repeatedly.

A number of experiments reveal that we can get a sense of satiety if we see the same image more 30 times. Tjark Andersen, who recently defended his PhD at Department of Food Science at Aarhus University, explains more.

"In our experiments, we showed that when the participants saw the same food picture 30 times, they felt more satiated than before they had seen the picture. The participants who were shown the picture many times also chose a smaller portion than those who had only seen the picture three times, when we subsequently asked about the size of portion they wanted," he says.

Tricking your brain into feeling full

It may sound strange that the participants felt full without actually eating anything. But this is really quite natural, explains Tjark Andersen. How we think about food has a large influence on our appetite.

"Your appetite is more closely linked with your cognitive perception than most of us think. How we think about our food is very important," he says, and continues:

"Studies have shown that if you make people aware of different colours of Jelly Beans, even if they have eaten all they can in red Jelly Beans, will still want the yellow ones. Even if both colours taste completely the same."

Within brain research, these findings are explained with so-called grounded cognition theory. For example, if you imagine putting your teeth in a juicy apple, the same areas of the brain are stimulated as if you actually take a bite of an apple.

"You will receive a physiological response to something you have only thought about. That's why we can feel fully satisfied without eating anything," he says.

A large online experiment

Tjark Andersen and his colleagues are not the first to discover that we can get feel full by looking at pictures of food. Other research groups have previously shown this.

The new research from Aarhus University is that they examined the number of repetitions needed -- and whether variation in the images removes the sense of satiety.

"We know from previous studies that images of different types of food don't have the same effect on satiety. That's why you can really feel full after the main course but still have room for dessert. Sweet things are a completely different type of food," he says.

To investigate whether variation in food completely removes the sense of satiety, Tjark Andersen and his colleagues designed a number of online experiments. They ended up getting more than 1,000 people through their digital experiments.

First they showed a picture of just orange M&Ms. Some participants were shown the picture three times, others 30 times. The group that saw most pictures the M&M felt most satiated afterwards, explains Tjark Andersen.

"They had to answer how many M&Ms between 1 and 10 they wanted. The group which had seen 30 images of orange chocolate buttons, chose a smaller amount than the other two groups."

Afterwards, they repeated the experiment. This time with M&Ms in different colours. The colours did not change the result.

Finally, they replaced the M&Ms with Skittles. Unlike M&Ss, Skittles taste different depending on the colour.

"If colour didn't play a role, it must be the imagined taste. But we found no major effect here either. This suggests that more parameters than just colour and flavour have to change before we can make a effect on satiety," he explains.

Could be used as a weight loss strategy

Since 1975, the number of overweight people worldwide has tripled. According to the WHO, obesity is one of the biggest health challenges facing humans. And the reason why we become too fat is that we eat too much food and too much unhealthy food and we do not take enough exercise.

This is where Tjark Andersen's results come into the play. Perhaps they can be applied as a method to control appetite, he says.

"Think if you developed an app based on a Google search. Let's say you wanted pizza. You open the app. Choose pizza -- and it shows a lot of photos of pizza while you imagine eating it. In this way, you could get a sense of satiety and maybe just stop wanting pizza."

Perhaps his results can best be used to ensure that you don't start a meal. The participants in the study only chose slightly fewer Skittles or M&Ms, corresponding to less than 50 calories.

"You won't save many calories unless you completely refrain from starting a meal. But perhaps the method can be used for this as well. It'd be interesting to investigate," he says.

Social media are overflowing with food

Tjark Andersen and a number of other researchers are studying how food advertisements on social media affect us, because we are constantly being confronted with delicious food.

A few years ago, an American research group tried to find out how many advertisements with food we encounter on average when we are on social media. The researchers monitored a number of young people and mapped out the content they met.

On average, the young people saw 6.1 of food-related posts in 12 hours. The vast majority of the posts were pictures of food -- and more than a third were about desserts or other sweet food.

The internet and, in particular, social media can be a contributory factor in our becoming increasingly overweight. But it may also be the solution.

Only the future will tell.

https://www.sciencedaily.com/releases/2023/05/230522131327.htm

Cannabinoids give worms the munchies, too

April 20, 2023

Science Daily/Cell Press

Marijuana (cannabis) is well known for giving people the "munchies." Not only does it make people want to eat more, but it also makes them crave the tastiest, most high-calorie foods. Now a new study in the journal Current Biology on April 20 shows that well-studied nematode worms (C. elegans) react to those chemicals known as cannabinoids in precisely the same way.

"Cannabinoids make nematodes hungrier for their favored foods and less hungry for their non-favored foods," says Shawn Lockery from the University of Oregon in Eugene. "Thus, the effects of cannabinoids in nematodes parallels the effects of marijuana on human appetites.

"Nematodes diverged from the lineage leading to mammals more than 500 million years ago," he added. "It is truly remarkable that the effects of cannabinoids on appetite are preserved through this length of evolutionary time."

Lockery explained that the new study was inspired in 2015, when cannabis became legal in Oregon. "At the time, our laboratory at the University of Oregon was deeply involved in assessing nematode food preferences as part of our research on the neuronal basis of economic decision-making," he said. "In almost literally a 'Friday afternoon experiment' -- read: 'let's dump this stuff on to see what happens' -- we decided to see if soaking worms in cannabinoids alters existing food preferences. It does, and the paper is the result of many years of follow-up research."

Cannabinoids are known to act by binding to cannabinoid detector proteins called cannabinoid receptors in the brain, nervous system, and other parts of the body. Those receptors in the body normally respond to related molecules that are naturally present in the body, known as endocannabinoids. The endocannabinoid system plays important roles in eating, anxiety, learning and memory, reproduction, metabolism, and more.

At the molecular level, the cannabinoid system in nematodes looks a lot like that in people and other animals. It begged the question as to whether the so-called hedonic feeding effects of cannabinoids also would be conserved across species.

In the new study, the researchers first showed that worms react to the endocannabinoid anandamide by eating more. They also ate more of their favorite food. The researchers found that those effects of the endocannabinoids depended on the presence of the worms' cannabinoid receptors.

In further studies, they genetically replaced the C. eleganscannabinoid receptor with the human cannabinoid receptor to see what would happen, and they found that the animals responded normally to cannabinoids. The discovery emphasizes the commonality of cannabinoid effects in nematodes and humans, the researchers say. They report that the effects of anandamide also depend on neurons that play a role in food detection.

"We found that the sensitivity of one of the main food-detecting olfactory neurons in C. elegans is dramatically altered by cannabinoids," Lockery said. "Upon cannabinoid exposure, it becomes more sensitive to favored food odors and less sensitive to non-favored food odors. This effect helps explain changes in the worm's consumption of food, and it is reminiscent of how THC makes tasty food even tastier in humans."

The findings in worms are not only entertaining, Lockery says, but they also have significant practical implications.

"Cannabinoid signaling is present in the majority of tissues in our body," he said. "It therefore could be involved in the cause and treatment of a wide range of diseases. The fact that the human cannabinoid receptor gene is functional in C. elegans food-choice experiments sets the stage for rapid and inexpensive screening for drugs that target a wide variety of proteins involved in cannabinoid signaling and metabolism, with profound implications for human health."

The researchers note that big outstanding questions remain, including how cannabinoids change the sensitivity of C. elegansolfactory neurons, which don't have cannabinoid receptors. They're also curious to study the effects of psychedelics on nematodes.

"Perhaps we can find a new set of similarities between humans and worms, now in the case of drugs that alter perception and psychological well-being," Lockery says.

https://www.sciencedaily.com/releases/2023/04/230420135331.htm

How to get your children to eat more fruits and vegetables

Study examines influence of longer family meals on children's eating behavior

April 18, 2023

Science Daily/Max Planck Institute for Human Development

Their experiment shows that children will eat significantly more fruits and vegetables if they on average stay at the table for only ten minutes more -- 30 minutes in total. On average, they ate about 100 grams more fruits and vegetables. This represents about one of the five recommended daily portions of fruits and vegetables and is as much as a small apple or a small bell pepper. The results of the study have been published in the US journal JAMA Network Open.

"This outcome has practical importance for public health because one additional daily portion of fruit and vegetables reduces the risk of cardiometabolic disease by 6 to 7 percent," explains Jutta Mata, professor of health psychology at the University of Mannheim. "For such an effect, a sufficient quantity of fruits and vegetables must be available on the table -- bite-sized pieces are best," the health psychologist adds.

50 pairs of parents and 50 children participated in the study. The average age of children in the study was 8 years and the average age of parents was 43 years. An equal number of boys and girls participated. The participants were served a typical German dinner with sliced bread, cold cuts, and cheese, as well as fruits and vegetables cut into bite-sized pieces.

"The duration of the meal is one of the central components of a family meal which parents can vary to improve the diet of their children. We had already found hints of this relation in a meta-analysis on studies looking at the qualitative components of healthy family meals. In this new experimental study, we were able to prove a formerly only correlative relationship," says Ralph Hertwig, Director at the Center for Adaptive Rationality of the Max Planck Institute for Human Development.

The study also shows that longer family meals did not lead to the children eating more bread or cold cuts; they also did not eat more dessert. Researchers assume that the bite-sized pieces of fruits and vegetables were easier to eat and thus more enticing.

https://www.sciencedaily.com/releases/2023/04/230418101408.htm

Kombucha to kimchi: Which fermented foods are best for your brain?

April 13, 2023

Science Daily/Microbiology Society

Many countries around the world have their own staple fermented foods which are ingrained into culture and diet. It can’t be a coincidence that this has happened again and again. It seems logical that fermented foods offer more than a method of preservation.? 

Diet can hugely impact your mental health and previous research has shown that some foods are particularly good at positively impacting your brain. Fermented foods are a source of tryptophan, an amino acid key to the production of serotonin, a messenger in the brain which influences several aspects of brain function, including mood. The foods may also contain other brain messengers (known as neurotransmitters) in their raw form. It’s no surprise then that research has shown that eating fermented foods may have various long- and short-term impacts on brain function, such as reducing stress. But which foods have the biggest impact on brain health?? 

Researchers at APC Microbiome, University College Cork, and Teagasc (Ireland’s Agriculture and Food Development Authority) in Moorepark, Cork, Ireland are currently working on a large study to finally answer this question. Ramya Balasubramanian and the team at APC compared sequencing data from over 200 foods from all over the world, looking for a variety of metabolites that are known to be beneficial to brain health.?? 

The study is still in it’s initial stages, but researchers are already surprised by preliminary results. Ramya explains, “I expected only a few fermented foods would show up, but out of 200 fermented foods, almost all of them showed the ability to exert some sort of potential to improve gut and brain health”. More research is needed to fully understand which groups of fermented foods have the greatest effects on the human brain, but results are showing an unexpected victor. 

“Fermented sugar-based products and fermented vegetable-based products are like winning the lottery when it comes to gut and brain health”, explains Ramya.  

“For all that we see on sugar-based products being demonised, fermented sugar takes the raw sugar substrate, and it converts it into a plethora of metabolites that can have a beneficial effect on the host. So even though it has the name ‘sugar’ in it, if you do a final metabolomic screen, the sugar gets used by the microbial community that's present in the food, and they get converted into these beautiful metabolites that are ready to be cherry picked by us for further studies.”? 

These further studies are what’s next for Ramya. She plans to put her top ranked fermented foods through rigorous testing using an artificial colon and various animal models to see how these metabolites affect the brain.?? 

Ramya hopes that the public can utilise these preliminary results and consider including fermented foods in their diet as a natural way of supporting their mental health and general well-being. 

https://www.sciencedaily.com/releases/2023/04/230413154458.htm

A higher dose of magnesium each day keeps dementia at bay

March 23, 2023

Science Daily/Australian National University

More magnesium in our daily diet leads to better brain health as we age, according to scientists from the Neuroimaging and Brain Lab at The Australian National University (ANU).

The researchers say increased intake of magnesium-rich foods such as spinach and nuts could also help reduce the risk of dementia, which is the second leading cause of death in Australia and the seventh biggest killer globally.

The study of more than 6,000 cognitively healthy participants in the United Kingdom aged 40 to 73 found people who consume more than 550 milligrams of magnesium each day have a brain age that is approximately one year younger by the time they reach 55 compared with someone with a normal magnesium intake of about 350 milligrams a day.

"Our study shows a 41 per cent increase in magnesium intake could lead to less age-related brain shrinkage, which is associated with better cognitive function and lower risk or delayed onset of dementia in later life," lead author and PhD researcher Khawlah Alateeq, from the ANU National Centre for Epidemiology and Population Health, said.

"This research highlights the potential benefits of a diet high in magnesium and the role it plays in promoting good brain health."

It's believed the number of people worldwide who will be diagnosed with dementia is expected to more than double from 57.4 million in 2019 to 152.8 million in 2050, placing a greater strain on health and social services and the global economy.

"Since there is no cure for dementia and the development of pharmacological treatments have been unsuccessful for the past 30 years, it's been suggested that greater attention should be directed towards prevention," study co-author Dr Erin Walsh, who is also from ANU, said.

"Our research could inform the development of public health interventions aimed at promoting healthy brain ageing through dietary strategies."

The researchers say a higher intake of magnesium in our diets from a younger age may safeguard against neurodegenerative diseases and cognitive decline by the time we reach our 40s.

"The study shows higher dietary magnesium intake may contribute to neuroprotection earlier in the ageing process and preventative effects may begin in our 40s or even earlier," Ms Alateeq said.

"This means people of all ages should be paying closer attention to their magnesium intake.

"We also found the neuroprotective effects of more dietary magnesium appears to benefit women more than men and more so in post-menopausal than pre-menopausal women, although this may be due to the anti-inflammatory effect of magnesium."

Participants completed an online questionnaire five times over a period of 16 months. The responses provided were used to calculate the daily magnesium intake of participants and were based on 200 different foods with varying portion sizes. The ANU team focused on magnesium-rich foods such as leafy green vegetables, legumes, nuts, seeds and wholegrains to provide an average estimation of magnesium intake from the participants' diets.

https://www.sciencedaily.com/releases/2023/03/230323103415.htm

Sweets change our brain

Why we can't keep our hands off chocolate bars and co.

March 22, 2023

Science Daily/Max-Planck-Gesellschaft

Chocolate bars, crisps and fries -- why can't we just ignore them in the supermarket? Researchers at the Max Planck Institute for Metabolism Research in Cologne, in collaboration with Yale University, have now shown that foods with a high fat and sugar content change our brain: If we regularly eat even small amounts of them, the brain learns to consume precisely these foods in the future.

Why do we like unhealthy and fattening foods so much? How does this preference develop in the brain? "Our tendency to eat high-fat and high-sugar foods, the so-called Western diet, could be innate or develop as a result of being overweight. But we think that the brain learns this preference," explains Sharmili Edwin Thanarajah, lead author of the study.

To test this hypothesis, the researchers gave one group of volunteers a small pudding containing a lot of fat and sugar per day for eight weeks in addition to their normal diet. The other group received a pudding that contained the same number of calories but less fat. The volunteer's brain activity was measured before and during the eight weeks.

Our brain unconsciously learns to prefer high-fat snacks

The brain's response to high-fat and high-sugar foods was greatly increased in the group that ate the high-sugar and high-fat pudding after eight weeks. This particularly activated the dopaminergic system, the region in the brain responsible for motivation and reward. "Our measurements of brain activity showed that the brain rewires itself through the consumption of chips and co. It subconsciously learns to prefer rewarding food. Through these changes in the brain, we will unconsciously always prefer the foods that contain a lot of fat and sugar," explains Marc Tittgemeyer, who led the study.

During the study period, the test persons did not gain more weight than the test persons in the control group and their blood values, such as blood sugar or cholesterol, did not change either. However, the researchers assume that the preference for sugary foods will continue after the end of the study. "New connections are made in the brain, and they don't dissolve so quickly. After all, the whole point of learning is that once you learn something, you don't forget it so quickly," explains Marc Tittgemeyer.

https://www.sciencedaily.com/releases/2023/03/230322140934.htm