The skinny on why poor sleep may increase heart risk in women
February 17, 2020
Science Daily/Columbia University Irving Medical Center
Women who sleep poorly tend to overeat and consume a lower-quality diet, according to a new study from researchers at Columbia University Irving Medical Center. The findings provide new insight into how poor sleep quality can increase the risk of heart disease and obesity and points to possible interventions for improving women's heart health.
Previous studies have shown that people who get less sleep are more likely to develop obesity, type 2 diabetes, and heart disease -- and that the relationship may be partially explained by diet. But these studies were narrowly focused on specific foods or nutrients (such as fish, sweets, or saturated fat) or only measured sleep duration, not sleep quality.
The new study was designed to get a more comprehensive picture in women by examining associations between overall diet quality and multiple aspects of sleep quality.
"Women are particularly prone to sleep disturbances across the life span, because they often shoulder the responsibilities of caring for children and family and, later, because of menopausal hormones," says Brooke Aggarwal, EdD, assistant professor of medical sciences at Columbia University Vagelos College of Physicians and Surgeons and senior author of the study.
The study of nearly 500 women was published online today in the Journal of the American Heart Association.
The researchers analyzed the sleep and eating habits of an ethnically diverse group of 495 women, ages 20 to 76. The study looked at sleep quality, the time it took to fall asleep, and insomnia. The women also reported on the types and amounts of foods they typically eat throughout the year, allowing researchers to measure their typical dietary patterns.
Similar to previous studies of sleep and diet, the study found that those with worse overall sleep quality consumed more of the added sugars associated with obesity and diabetes.
Women who took longer to fall asleep had higher caloric intake and ate more food by weight.
And women with more severe insomnia symptoms consumed more food by weight and fewer unsaturated fats than women with milder insomnia.
"Our interpretation is that women with poor-quality sleep could be overeating during subsequent meals and making more unhealthy food choices," says Aggarwal.
The question remains: How might poor sleep contribute to poor eating?
"Poor sleep quality may lead to excessive food and calorie intake by stimulating hunger signals or suppressing signals of fullness," says Faris Zuraikat, PhD, postdoctoral fellow at Columbia University Vagelos College of Physicians and Surgeons and lead author of the study. "Fullness is largely affected by the weight or volume of food consumed, and it could be that women with insomnia consume a greater amount of food in an effort to feel full.
"However, it's also possible that poor diet has a negative impact on women's sleep quality," adds Zuraikat. "Eating more could also cause gastrointestinal discomfort, for instance, making it harder to fall asleep or remain asleep."
"Given that poor diet and overeating may lead to obesity -- a well-established risk factor for heart disease -- future studies should test whether therapies that improve sleep quality can promote cardiometabolic health in women," says Aggarwal.
About the Study
The women in the study were participants in the American Heart Association's Go Red for Women Strategically Focused Research Network at Columbia University Irving Medical Center.
Two other research teams in Columbia's Go Red for Women network are studying the impact of sleep restriction on risk factors for heart disease and on the cells that line blood vessels.
The study is titled "Measures of Poor Sleep Quality Are Associated with Higher Energy Intake and Poor Diet Quality in a Diverse Sample of Women from the Go Red for Women Strategically Focused Research Network."
https://www.sciencedaily.com/releases/2020/02/200217085214.htm
Researchers discover brain circuit linked to food impulsivity
This creates the possibility scientists can someday develop therapeutics to address overeating
December 11, 2019
Science Daily/University of Georgia
A team of researchers has now identified a specific circuit in the brain that alters food impulsivity.
You're on a diet, but the aroma of popcorn in the movie theater lobby triggers a seemingly irresistible craving.
Within seconds, you've ordered a tub of the stuff and have eaten several handfuls.
Impulsivity, or responding without thinking about the consequences of an action, has been linked to excessive food intake, binge eating, weight gain and obesity, along with several psychiatric disorders including drug addiction and excessive gambling.
A team of researchers that includes a faculty member at the University of Georgia has now identified a specific circuit in the brain that alters food impulsivity, creating the possibility scientists can someday develop therapeutics to address overeating.
The team's findings were published recently in the journal Nature Communications.
"There's underlying physiology in your brain that is regulating your capacity to say no to (impulsive eating)," said Emily Noble, an assistant professor in the UGA College of Family and Consumer Sciences who served as lead author on the paper. "In experimental models, you can activate that circuitry and get a specific behavioral response."
Using a rat model, researchers focused on a subset of brain cells that produce a type of transmitter in the hypothalamus called melanin concentrating hormone (MCH).
While previous research has shown that elevating MCH levels in the brain can increase food intake, this study is the first to show that MCH also plays a role in impulsive behavior, Noble said.
"We found that when we activate the cells in the brain that produce MCH, animals become more impulsive in their behavior around food," Noble said.
To test impulsivity, researchers trained rats to press a lever to receive a "delicious, high-fat, high-sugar" pellet, Noble said. However, the rat had to wait 20 seconds between lever presses. If the rat pressed the lever too soon, it had to wait an additional 20 seconds.
Researchers then used advanced techniques to activate a specific MCH neural pathway from the hypothalamus to the hippocampus, a part of the brain involved with learning and memory function.
Results indicated MCH doesn't affect how much the animals liked the food or how hard they were willing to work for the food. Rather, the circuit acted on the animals' inhibitory control, or their ability to stop themselves from trying to get the food. "Activating this specific pathway of MCH neurons increased impulsive behavior without affecting normal eating for caloric need or motivation to consume delicious food," Noble said. "Understanding that this circuit, which selectively affects food impulsivity, exists opens the door to the possibility that one day we might be able to develop therapeutics for overeating that help people stick to a diet without reducing normal appetite or making delicious foods less delicious."
https://www.sciencedaily.com/releases/2019/12/191211145630.htm
Overweight kids actually eat less right after stressful events
September 3, 2019
Science Daily/University of Michigan
A new study recently found that overweight adolescents -- considered particularly susceptible to stress eating -- actually ate less when exposed to a lab stressor.
People often react to stress by binging on sweets or fattening comfort foods, cravings fueled by the appetite-stimulating stress hormone cortisol.
But overweight adolescents -- considered particularly susceptible to stress eating -- actually ate less when exposed to a lab stressor, and the foods they eschewed were the high fat and sugar options, according to a University of Michigan study.
Even more surprising, kids who produced the most cortisol after the stressor saw the biggest appetite reduction, eating about 35% fewer calories in the two hours after the stressor, said principal investigator Rebecca Hasson, associate professor of movement science at the U-M School of Kinesiology.
Results were similar whether adolescents in the study were monitoring their food intake or not. This matters because people who restrict calories are more likely to stress eat.
That didn't happen among these dieters, and the results suggest that a biological response -- such as the flood of cortisol or the satiety hormone leptin -- drove the adolescents' reduced appetite.
Hasson and colleague Matthew Nagy, the study's first author and an alumnus of the U-M School of Public Health, wanted to understand how biology and behavior impacted the eating patterns of overweight kids.
"These are really exciting findings because they give us a chance to observe eating patterns when adults are exposed to stress, which is a very important factor in childhood obesity, long-term cardiovascular risk and type 2 diabetes risk," said Hasson, who also leads the U-M Childhood Disparities Research Lab and is an associate professor of nutritional sciences in the School of Public Health.
"This doesn't mean stress kids out and they'll lose weight. This is in the short term only. They may eat more calories later. Typically, many kids did say they turned to food when stressed, so maybe this was a time effect."
Also, even if the cortisol spike didn't cause overeating, it's still metabolically unhealthy, she said.
The study, which appears in Psychosomatic Medicine, involved about 60 kids.
Hasson said much work remains to see who's susceptible to big cortisol spikes and the long-term effects of stress. Previous studies have found that overweight adults with high cortisol responses after stress also experience short-term calorie reduction.
https://www.sciencedaily.com/releases/2019/09/190903084044.htm
Scientists find brain mechanism that naturally combats overeating
March 28, 2019
Science Daily/Rockefeller University
Studying a brain region involved in memory, researchers discovered a set of neurons that help mice control their appetite.
Food is, generally speaking, a good thing. In addition to being quite tasty, it is also necessary for survival. That's why animals have evolved robust physiological systems that attract them to food and keep them coming back for more.
Now, research in mice reveals the existence of brain cells that have the opposite effect, curbing an animal's impulse to eat. Published in Neuron, the study shows that these cells also play a role in regulating memory, and are part of a larger brain circuit that promotes balanced eating.
The belly and the brain
Historically, researchers have thought of feeding as a visceral, instinctive process: An animal smells or sees an appealing snack and, without hesitation, proceeds to eat said snack. However, an increasingly detailed picture is now emerging in which mental processes inform animals' decision to either consume or refuse a meal.
A human, for example, may consider, "I'm supposed to be at brunch in 20 minutes, so I better save my appetite." Though other mammals may not have the equivalent internal monologue, there is reason to suspect that their eating habits do involve complex cognition. For example, research has shown that defects in the hippocampus -- a brain area involved in memory -- can alter feeding behavior, suggesting that past experiences influence an animal's attraction to food.
Building on this research, Estefania Azevedo, a postdoctoral associate in the lab of Jeffrey M. Friedman, recently identified a group of hippocampal cells, known as hD2R neurons, that become active whenever a mouse is fed. Collaborating with Paul Greengard, the Vincent Astor Professor, and Jia Cheng, a postdoctoral associate in his lab, the researchers also found that when these neurons were stimulated, mice ate less; and when they were silenced, they ate more. In short, hD2R neurons respond to the presence of food by deterring animals from eating that food.
Interpreting these findings, Azevedo says that, though animals usually benefit from eating the snacks in front of them, in some instances it is useful to exercise restraint. For example, if an animal has recently eaten, then searching for another meal is both unnecessary and risky, as foraging exposes animals to predators. The newly discovered neurons, it seems, help animals stop feeding when it no longer behooves them.
"These cells keep an animal from overeating," says Azevedo. "They appear to make eating less rewarding and, in that sense, are tuning the animal's relationship to food."
Everything in moderation
In the wild, you can't eat unless you know where to find food. Fortunately, brains are quite good at remembering the location of past meals: When an animal encounters sustenance in a particular locale, it makes a mental connection between the place and the food. To test how hD2R cells might affect these connections, Friedman and Azevedo stimulated the neurons as mice wandered around a food-filled environment. This intervention, they found, made mice less likely to return to the area in which food was previously located -- suggesting that hDR2 activation somehow diminishes meal-related memories.
"Mental connections between food and location are important for survival, and the strength of these connections is regulated by how rewarding an experience is," says Azevedo. "Because hD2R neurons affect an animal's relationship with food, it also ends up affecting these connections."
Further experiments showed that hD2R neurons receive input from the entorhinal cortex, which processes sensory information, and send output to the septum, which is involved in feeding. The first to identify this brain circuit, the researchers conclude that the neurons serve as a regulatory checkpoint between sensing food and eating food.
Together with analyses of other neural circuits, this research suggests that the brain has elaborate mechanisms for fine-tuning appetite: While some systems help an animal remember and find food, others restrain food intake.
"Our study shows that brain areas involved in cognitive processing and memory formation affect feeding behavior," says Azevedo. "So it is possible that, with training, people may be able to learn to change their relationship to food."
https://www.sciencedaily.com/releases/2019/03/190328150732.htm
Food for thought: How the brain reacts to food may be linked to overeating
July 19, 2018
Science Daily/Penn State
The reason why some people find it so hard to resist finishing an entire bag of chips or bowl of candy may lie with how their brain responds to food rewards, according to researchers who found that when certain regions of the brain reacted more strongly to being rewarded with food than being rewarded with money, those people were more likely to overeat.
In a study with children, researchers found that when certain regions of the brain reacted more strongly to being rewarded with food than being rewarded with money, those children were more likely to overeat, even when the child wasn't hungry and regardless of if they were overweight or not.
Shana Adise, a postdoctoral fellow at the University of Vermont who led the study while earning her doctorate at Penn State, said the results give insight into why some people may be more prone to overeating than others. The findings may also give clues on how to help prevent obesity at a younger age.
"If we can learn more about how the brain responds to food and how that relates to what you eat, maybe we can learn how to change those responses and behavior," Adise said. "This also makes children an interesting population to work with, because if we can stop overeating and obesity at an earlier age, that could be really beneficial."
Previous research on how the brain's response to food can contribute to overeating has been mixed. Some studies have linked overeating with brains that are more sensitive to food rewards, while others have found that being less sensitive to receiving food rewards makes you more likely to overeat.
Additionally, other studies have shown that people who are willing to work harder for food than other types of rewards, like money, are more likely to overeat and gain weight over time. But the current study is the first to show that children who have greater brain responses to food compared to money rewards are more likely to overeat when appealing foods are available.
"We know very little about the mechanisms that contribute to overeating," Adise said. "The scientific community has developed theories that may explain overeating, but whether or not they actually relate to food intake hadn't yet been evaluated. So we wanted to go into the lab and test whether a greater brain response to anticipating and winning food, compared to money, was related to overeating."
For the study, 59 children between the ages of 7 and 11 years old made four visits to the Penn State's Children's Eating Behavior Laboratory.
During the first three visits, the children were given meals designed to measure how they eat in a variety of different situations, such as a typical meal when they're hungry versus snacks when they're not hungry. How much the children ate at each meal was determined by weighing the plates before and after the meals.
On their fourth visit, the children had fMRI scans as they played several rounds of a game in which they guessed if a computer-generated number would be higher or lower than five. They were then told that if they were right, they would win either money, candy or a book, before it was revealed if they were correct or not.
The researchers found that when various regions of the brain reacted more to anticipating or winning food compared to money, those children were more likely to overeat.
"We also found that the brain's response to food compared to money was related to overeating regardless of how much the child weighed," Adise said. "Specifically, we saw that increased brain responses in areas of the brain related to cognitive control and self control when the children received food compared to money were associated with overeating."
Adise added that this is important because it suggests there may be a way to identify brain responses that can predict the development of obesity in the future.
Kathleen Keller, associate professor of nutritional sciences, Penn State, said the study -- recently published in the journal Appetite -- backs up the theory that an increased brain response in regions of the brain related to rewards is associated with eating more food in a variety of situations.
"We predicted that kids who had an increased response to food relative to money would be the ones to overeat, and that's what we ended up seeing," Keller said. "We specifically wanted to look at kids whose brains responded to one type of a reward over another. So it wasn't that they're overly sensitive to all rewards, but that they're highly sensitive to food rewards."
Keller said the findings give insight into how the brain influences eating, which is important because it could help identify children who are at risk for obesity or other poor eating habits before those habits actually develop.
"Until we know the root cause of overeating and other food-related behaviors, it's hard to give good advice on fixing those behaviors," Keller said. "Once patterns take over and you overeat for a long time, it becomes more difficult to break those habits. Ideally, we'd like to prevent them from becoming habits in the first place."
https://www.sciencedaily.com/releases/2018/07/180719085413.htm