Vegetarians tend to be slimmer and less extroverted than meat eaters

June 15, 2020

Science Daily/Max Planck Institute for Human Cognitive and Brain Sciences

The less animal products someone consumes, the lower his body mass index on average and the less he tends to be extroverted. A connection with depressive moods as other studies had found could not be confirmed.

According to a survey by the Allensbach Institute, more than 6.1 million Germans stated last year that they were vegetarians, 400,000 more than two years earlier. A large-scale study at the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in cooperation with the University Hospital of Leipzig has now examined in almost 9,000 people how this form of nutrition is related to the body and the psyche -- regardless of age, gender and level of education.

It was found that the rarer the proportion of animal food in a person's diet, the lower their body mass index (BMI) on average and thus their body weight. One reason for this could be the lower proportion of heavily processed foods in the plant diet. "Products that are excessively rich in fat and sugar are particularly fattening. They stimulate the appetite and delay the feeling of satiety. If you avoid animal foods, you consume fewer such products on average," explains Evelyn Medawar, first author of the underlying publication, which has now been published in the journal Nutrients. In addition: Vegetarian food contains dietary fibres and has a positive effect on the microbiome in the intestine. This is another reason why they could fill you up earlier than those made from animal ingredients. "People who eat predominantly vegetable foods may therefore absorb less energy," Medawar adds. In addition to a changed feeling of satiety, lifestyle factors such as more sport and greater health awareness could also play a decisive role.

For the BMI it also seems to make a difference which animal products a person feeds on. If it is predominantly so-called primary animal products, i.e. meat, sausage and fish, the person usually has a higher BMI than someone who eats primarily secondary animal products, i.e. eggs, milk, dairy products, cheese and butter. In the former case the correlation is statistically significant.

Medawar uses an example to illustrate what this could mean for nutrition: "A person with a 1.2 point lower BMI on average either completely avoids certain animal products, such as the primary ones, and is on a vegetarian diet. Or she continues to eat meat and fish, but less often. Whether nutrition is ultimately the cause of lower body weight or whether other factors are responsible for it cannot be determined from the data. A follow-up study in cooperation with the University Hospital Leipzig will now shed light on this.

Nutrition and personality

The researchers also found out that vegetarian or vegan nutrition is also related to personality. Especially with one of the five major personality factors, extroversion. It was shown that people with predominantly plant-based foods on their diet are more introverted than those who mainly fed on animal products. "It is difficult to say what the reason for this is," says Veronica Witte. "It could be because more introverted people tend to have more restrictive eating habits or because they are more socially segregated because of their eating habits." Here, again, further studies should follow on how people identify with the characteristics of their diet.

However, they could not confirm that a plant-based diet is associated with a tendency towards neurotic behaviour, as other studies suggested. "Earlier analyses had found that more neurotic people were generally more likely to avoid certain groups of foods and to behave more restrictively. We focused here solely on the avoidance of animal products and could not observe any correlation," explains study leader Veronica Witte.

In a third part, they finally concentrated on the question of whether a predominantly plant-based diet is more often associated with depressive moods. Here previous studies had also suggested a relationship between the two factors. "We could not detect this correlation," says Witte. "It is possible that in previous analyses other factors had blurred the results, including the BMI or conspicuous personality traits that are known to be associated with depression. We accounted for them," said Witte explaining a possible reason for the different results. In addition, the plant-based diet is now more common and more accepted and not anymore restricted to a certain group.

The scientists had investigated these connections within the so-called LIFE project, a broad-based study in cooperation with the University Hospital of Leipzig. They determined the personal diets by means of questionnaires in which the participants were asked to fill in how often they had eaten the individual animal products in the last 12 months -- from "several times a day" to "never." The personality traits such as extroversion and neuroticism were assessed by means of a so-called personality inventory (NEOFFI), while depression was assessed by means of the so-called CESD test, a questionnaire that records various symptoms of depression.

https://www.sciencedaily.com/releases/2020/06/200615115748.htm

Losing tongue fat improves sleep apnea

Tongue could be a new target for treating the common sleep disorder

January 10, 2020

Science Daily/University of Pennsylvania School of Medicine

Using magnetic resonance imaging (MRI) to measure the effect of weight loss on the upper airway in obese patients, researchers found that reducing tongue fat is a primary factor in lessening the severity of OSA.

Losing weight is an effective treatment for Obstructive Sleep Apnea (OSA), but why exactly this is the case has remained unclear. Now, researchers in the Perelman School of Medicine at the University of Pennsylvania have discovered that improvements in sleep apnea symptoms appear to be linked to the reduction of fat in one unexpected body part -- the tongue.

Using magnetic resonance imaging (MRI) to measure the effect of weight loss on the upper airway in obese patients, researchers found that reducing tongue fat is a primary factor in lessening the severity of OSA. The findings were published today in the American Journal of Respiratory and Critical Care Medicine.

"Most clinicians, and even experts in the sleep apnea world, have not typically focused on fat in the tongue for treating sleep apnea," said Richard Schwab, MD, chief of Sleep Medicine. "Now that we know tongue fat is a risk factor and that sleep apnea improves when tongue fat is reduced, we have established a unique therapeutic target that we've never had before."

Twenty-two million Americans suffer from sleep apnea, a serious health condition in which breathing repeatedly stops and starts, causing patients to wake up randomly throughout their sleep cycles. The condition, which is usually marked by loud snoring, can increase your risk for high blood pressure and stroke. While obesity is the primary risk factor for developing sleep apnea, there are other causes, such as having large tonsils or a recessed jaw. CPAP (continuous positive airway pressure) machines improves sleep apnea in about 75 percent of patients, studies suggest, but for the other 25 percent -- those who may have trouble tolerating the machine -- alternative treatment options, such as oral appliances or upper airway surgery, are more complicated.

A 2014 study led by Schwab compared obese patients with and without sleep apnea, and found that the participants with the condition had significantly larger tongues and a higher percentage of tongue fat when compared to those without sleep apnea. The researchers next step was to determine if reducing tongue fat would improve symptoms and to further examine cause and effect.

The new study included 67 participants with mild to severe obstructive sleep apnea who were obese -- those with a body mass index greater than 30.0. Through diet or weight loss surgery, the patients lost nearly 10 percent of their body weight, on average, over six months. Overall, the participants' sleep apnea scores improved by 31 percent after the weight loss intervention, as measured by a sleep study.

Before and after the weight loss intervention, the study participants underwent MRI scans to both their pharynx as well as their abdomens. Then, using a statistical analysis, the research team quantified changes between overall weight loss and reductions to the volumes of the upper airway structures to determine which structures led to the improvement in sleep apnea. The team found that a reduction in tongue fat volume was the primary link between weight loss and sleep apnea improvement.

The study also found that weight loss resulted in reduced pterygoid (a jaw muscle that controls chewing) and pharyngeal lateral wall (muscles on the sides of the airway) volumes. Both these changes also improved sleep apnea, but not to the same extent as the reduction in tongue fat.

The authors believe that tongue fat is a potential new therapeutic target for improving sleep apnea. They suggest that future studies could be designed to explore whether certain low-fat diets are better than others in reducing tongue fat and whether cold therapies -- like those used to reduce stomach fat -- might be applied to reducing tongue fat. However, Schwab notes, these types of interventions have not yet been tested.

Schwab's team is also examining new interventions and other risk factors for sleep apnea, including whether some patients who are not obese but who have "fatty" tongues could be predisposed to sleep apnea, but are less likely to be diagnosed.

In a recent related study, Schwab found that ethnicity may also play a role in sleep apnea severity. His research team compared the upper airway anatomy of Chinese and Icelandic patients with sleep apnea, and found that, compared to Icelandic patients of similar age, gender, and symptoms, Chinese patients had smaller airways and soft tissues, but bigger soft palate volume with more bone restrictions. This means that Asian patients may generally be more at risk for severe sleep apnea symptoms. The bottom line, according to Schwab, is that all patients who suffer from snoring or sleepiness should be screened for sleep apnea, whether or not they appear to fall into the typical "high-risk" obese categories.

"Primary care doctors, and perhaps even dentists, should be asking about snoring and sleepiness in all patients, even those who have a normal body mass index, as, based on our data, they may also be at risk for sleep apnea," Schwab said.

https://www.sciencedaily.com/releases/2020/01/200110101035.htm

Slim people have a genetic advantage when it comes to maintaining their weight

January 24, 2019

Science Daily/University of Cambridge

In the largest study of its kind to date, researchers have looked at why some people manage to stay thin while others gain weight easily. They have found that the genetic dice are loaded in favor of thin people and against those at the obese end of the spectrum.

More than six in ten adults in the UK are overweight, and one in four adults is obese. By age five, almost one in four children is either overweight or obese. Excess weight increases the risk of related health problems including type 2 diabetes and heart disease.

While it is well known that changes in our environment, such as easy access to high calorie foods and sedentary lifestyles, have driven the rise in obesity in recent years, there is considerable individual variation in weight within a population that shares the same environment. Some people seem able to eat what they like and remain thin. This has led some people to characterise overweight people as lazy or lacking willpower.

With support from Wellcome and the European Research Council, a team led by Professor Sadaf Farooqi at the Wellcome-MRC Institute of Metabolic Science, University of Cambridge, established the Study Into Lean and Thin Subjects -- STILTS -- to examine why and how some people find it easier to stay thin than others. Studies of twins have shown that variation in body weight is largely influenced by our genes. To date studies have overwhelmingly focused on people who are overweight. Hundreds of genes have been found that increase the chance of a person being overweight and in some people faulty genes can cause severe obesity from a young age.

Professor Sadaf Farooqi's team were able to recruit 2,000 people who were thin (defined as a body mass index (BMI) of less than 18 kg/m2) but healthy, with no medical conditions or eating disorders. They worked with general practices across the UK, taking saliva samples to enable DNA analysis and asking participants to answer questions about their general health and lifestyles. It is thought to be the only cohort of its kind in the world and the researchers say that the UK's National Institute for Health Research -- the National Health Service's research infrastructure -- strongly enabled and supported their research.

In a study published today in the journal PLOS Genetics, Professor Farooqi's team collaborated with Dr Inês Barroso's team at the Wellcome Sanger Institute to compare the DNA of some 14,000 people -1,622 thin volunteers from the STILTS cohort, 1,985 severely obese people and a further 10,433 normal weight controls.

Our DNA comprises of a sequence of molecules known as base pairs, represented by the letters A, C, G and T. Strings of these base pairs form genetic regions (which include or make up our genes). Our genes provide the code for how our body functions and changes in the spelling -- for example, a C in place of an A -- can have subtle or sometimes dramatic changes on features such as hair colour and eye colour but also on a person's weight.

The team found several common genetic variants already identified as playing a role in obesity. In addition, they found new genetic regions involved in severe obesity and some involved in healthy thinness.

To see what impact these genes had on an individual's weight, the researchers added up the contribution of the different genetic variants to calculate a genetic risk score.

"As anticipated, we found that obese people had a higher genetic risk score than normal weight people, which contributes to their risk of being overweight. The genetic dice are loaded against them," explains Dr Barroso.

Importantly, the team also showed that thin people, had a much lower genetic risk score -- they had fewer genetic variants that we know increase a person's chances of being overweight.

"This research shows for the first time that healthy thin people are generally thin because they have a lower burden of genes that increase a person's chances of being overweight and not because they are morally superior, as some people like to suggest," says Professor Farooqi. "It's easy to rush to judgement and criticise people for their weight, but the science shows that things are far more complex. We have far less control over our weight than we might wish to think."

Three out of four people (74%) in the STILTS cohort had a family history of being thin and healthy and the team found some genetic changes that were significantly more common in thin people, which they say may allow them to pinpoint new genes and biological mechanisms that help people stay thin.

"We already know that people can be thin for different reasons" says Professor Farooqi. "Some people are just not that interested in food whereas others can eat what they like, but never put on weight. If we can find the genes that prevent them from putting on weight, we may be able to target those genes to find new weight loss strategies and help people who do not have this advantage."

https://www.sciencedaily.com/releases/2019/01/190124141538.htm

Treating obesity: One size does not fit all

November 13, 2018

Science Daily/Brown University

Understanding the very different characteristics of subgroups of obese patients may hold the key to devising more effective treatments and interventions, new research found.

Analyzing data from more than 2,400 obese patients who underwent bariatric weight-loss surgery, researchers identified at least four different patient subgroups that diverge significantly in eating behaviors and rate of diabetes, as well as weight loss in three years after surgery.

"There probably isn't one magic bullet for obesity -- if there is a magic bullet, it's going to be different for different groups of people," said Alison Field, chair of the department of epidemiology at the Brown University School of Public Health and lead author of the paper.

"There's a really diverse mix of people who get put into one group. A child who becomes very obese by age 5 is going to be very different from someone who gradually gains weight over time and at age 65 is obese. We need to recognize this diversity, as it may help us to develop more personalized approaches to treating obesity."

The findings were published on Tuesday, Nov. 13, in the journal Obesity.

Four groups of patients

This was the first study examine psychological variables, such as eating patterns, weight history and a range of biological variables, including hormone levels, to identify different types of obesity, Field said.

The team used an advanced computational model, called latent class analysis, to identify different groups of patients among more than 2,400 adults who underwent bariatric surgery between March 2006 and April 2009 -- either gastric bypass or gastric banding. They found four distinct groups.

Group one was characterized by low levels of high-density lipoprotein, the so called "good" cholesterol, and very high levels of glucose in their blood prior to surgery. In fact, 98 percent of this group's members were diabetic, in contrast with the other groups, where about 30 percent were diabetic, the study found.

Group two was characterized by disordered eating behaviors. Specifically, 37 percent had a binge eating disorder, 61 percent reported feeling a loss of control over "grazing" -- regularly eating food between meals -- and 92 percent reported eating when they weren't hungry.

Field found group three surprising, she said. Metabolically, they were fairly average, but they had very low levels of disordered eating -- only 7 percent reported eating when they weren't hungry compared to 37 percent for group one, 92 percent for group two and 29 percent for group four.

"Interestingly, no other factors distinguished this group from the other classes," the authors reported in the paper.

Group four comprised individuals who had been obese since childhood. This group had the highest body mass index (BMI) at age 18 with an average of 32, compared to an average of approximately 25 for the other three groups. A BMI above 30 is considered obese, while 25 is the start of the range defined as overweight. This group also had the highest pre-surgery BMI, an average of 58 compared to approximately 45 for the other three groups, the study reported.

Overall, in the three years following the bariatric procedure, men lost an average of 25 percent of pre-surgery weight and women lost an average of 30 percent. Field and colleagues found that patients in groups two and three benefited more from bariatric surgery than patients in groups one and four. Men and women with disordered eating lost the most, at an average of 28.5 percent and 33.3 percent, respectively, of pre-surgery weight.

Targeted treatments

Identifying these different groups of patients and understanding their characteristics should help obesity research and treatment, Field said. At the extreme end of treatment -- procedures such as bariatric surgery -- it's important to identify who would benefit most from surgery and those for whom the benefits likely won't outweigh the surgical risks, she said.

"One of the reasons why we haven't had stronger findings in the field of obesity research is that we're classifying all of these people as the same," Field said. "It may very well be that there are some incredibly effective strategies out there for preventing or treating obesity, but when you mix patients of different groups together, it dilutes the effect."

Field added that obesity researchers need to test a variety of interventions in a more targeted, personalized manner. For example, mindfulness might be quite effective for people who are overstimulated by the sights and smells of food but might not be effective for people in group three who don't eat when they're not hungry, she said.

In the future, Field hopes to use the same statistical analysis methods on a more general population of overweight individuals to see if the same, or similar, subgroups exist among people at weights less than those defined as obese.

She and her colleagues are now developing a mobile app to measure what influences individuals' eating behaviors in real time. Field hopes the app can eventually be used to provide tailored interventions. She has a beta version of the app, and hopes to move forward in fully developing and testing it.

https://www.sciencedaily.com/releases/2018/11/181113080923.htm

Obesity increases dementia risk

November 30, 2017

Science Daily/University College London

People who have a high body mass index (BMI) are more likely to develop dementia than those with a normal weight, according to a new study.

The study, published in the Alzheimer's & Dementia journal, analysed data from 1.3 million adults living in the United States and Europe. The researchers also found that people near dementia onset, who then go on to develop dementia, tend to have lower body weight than their dementia-free counterparts.

"The BMI-dementia association observed in longitudinal population studies, such as ours, is actually attributable to two processes," said lead author of the study, Professor Mika Kivimäki (UCL Institute of Epidemiology & Health). "One is an adverse effect of excess body fat on dementia risk. The other is weight loss due to pre-clinical dementia. For this reason, people who develop dementia may have a higher-than-average body mass index some 20 years before dementia onset, but close to overt dementia have a lower BMI than those who remain healthy."

"The new study confirms both the adverse effect of obesity as well as weight loss caused by metabolic changes during the pre-dementia stage."

Past research on how a person's weight influences their risk of dementia has produced conflicting results. Some findings have suggested that being obese poses a higher dementia risk, but other studies have linked lower weight to increased dementia incidence.

In this study, researchers from across Europe pooled individual-level data from 39 longitudinal population studies from the United States, the United Kingdom, France, Sweden, and Finland. A total of 1,349,857 dementia-free adults participated in these studies and their weight and height were assessed. Dementia was ascertained using linkage to electronic health records obtained from hospitalisation, prescribed medication and death registries.

A total of 6,894 participants developed dementia during up to 38 years of follow-up. Two decades before symptomatic dementia, higher BMI predicted dementia occurrence: each 5-unit increase in BMI was associated with a 16-33% higher risk of this condition (5 BMI units is 14.5kg for a person 5'7" (170cm) tall, approximately the difference in weight between the overweight and normal weight categories or between the obese and overweight categories). In contrast, the mean level of BMI during pre-clinical stage close to dementia onset was lower compared to that in participants who remained healthy.

In 2015, the number of people with dementia reached almost 45 million, two times more than in 1990. This study suggests that maintaining a healthy weight could prevent, or at least delay, dementia.

https://www.sciencedaily.com/releases/2017/11/171130133812.htm

Light exposure and kids' weight: Is there a link?

World-first study revealing light exposure plays a role in the weight of preschool children

January 7, 2016

Science Daily/Queensland University of Technology

Light exposure plays a role in the weight of preschool children, a world-first study reveals. The researchers studied children aged three to five, from six childcare centers, measuring the children's sleep, activity and light exposure for a two week period, along with height and weight to calculate their BMI, then followed up 12-months later.

https://images.sciencedaily.com/2016/01/160107104820_1_540x360.jpg

Around 42 million children around the globe under the age of five are classified as overweight or obese so this study is a significant breakthrough and a world-first, say the researchers.

Credit: © TuTheLens / Fotolia

PhD student Cassandra Pattinson and colleagues Simon Smith, Alicia Allan, Sally Staton and Karen Thorpe studied children aged three to five, from six Brisbane childcare centres. At time 1, they measured children's sleep, activity and light exposure for a two week period, along with height and weight to calculate their BMI, then followed up 12-months later

"At time 1, we found moderate intensity light exposure earlier in the day was associated with increased body mass index (BMI) while children who received their biggest dose of light -- outdoors and indoors -- in the afternoon were slimmer," said Ms Pattinson of the Environmental Light Exposure is Associated with Increased Body Mass in Children study.

"At follow-up, children who had more total light exposure at Time 1 had higher body mass 12 months later. Light had a significant impact on weight even after we accounted for Time 1 body weight, sleep, and activity.

"Around 42 million children around the globe under the age of five are classified as overweight or obese so this is a significant breakthrough and a world-first.

"Artificial lighting, including light given off by tablets, mobile phones, night lights, and television, means modern children are exposed to more environmental light than any previous generation. This increase in light exposure has paralleled global increases in obesity."

The research team is from QUT's Institute of Health and Biomedical Innovation and the Centre for Children's Health Research

Ms Pattinson said it is known the timing, intensity and duration of exposure to both artificial and natural light have acute biological effects in mammals.

"The circadian clock -- also known as the internal body clock -- is largely driven by our exposure to light and the timing of when that happens. It impacts on sleep patterns, weight gain or loss, hormonal changes and our mood," Ms Pattinson said

"Factors that impact on obesity include calorie intake, decreased physical activity, short sleep duration, and variable sleep timing. Now light can be added to the mix."

Ms Pattinson said the next step was to figure out how the research can be used in the fight against obesity in children.

"We plan to conduct further studies with pre-schoolers and also infants," she said.

"Animal studies have shown that timing and intensity of light exposure is critical for metabolic functioning and weight status. Our findings suggest that the same applies to us.

"This research suggests that exposure to different types of light (both artificial and natural) at different times now needs to be part of the conversation about the weight of children."

http://www.sciencedaily.com/releases/2016/01/160107104820.htm