Study: Brain key to keeping weight off

Why do some people who lose weight keep it off, while others gain the pounds right back? A new study from The Miriam Hospital shows their brains’ response to the sight of food might be making the difference.
The study, published in the American Journal of Clinical Nutrition, found that when people who have kept weight off for several years were shown pictures of food, they were likelier than obese or even normal-weight people to engage the areas of the brain associated with behavioral control and visual attention.
The findings “provide an intriguing complement to previous behavioral studies that suggest people who have maintained a long-term weight loss monitor their food intake closely and exhibit restraint in their food choices,” said lead author Jeanne McCaffery, of the hospital’s Weight Control and Diabetes Research Center.
Keeping pounds off remains a major challenge in obesity treatment. Participants in behavioral weight loss programs lose an average of 8 to 10 percent of their weight in their first six months of treatment and keep about two-thirds of the weight off for the first year.
But within five years, most patients have returned to their original weight.
The study used functional magnetic resource imaging (fMRI), a non-invasive technique that localizes regions of the brain activated during cognition and experience, to study the brain activity of three groups: 18 individuals of normal weight, 16 obese individuals (defined as a body mass index of at least 30), and 17 participants who have lost at least 30 pounds and kept the weight off for at least three years.
The participants were asked to fast for four hours to ensure they’d be hungry. Then they were shown pictures of food, including low-calorie items such as whole-grains cereals, salads, fruits and vegetables; high-calorie items such as cheeseburgers, hot dogs, ice cream and cake; and non-food objects with similar visual complexity, texture and color, such as rocks, shrubs, trees and flowers. The fMRI documented brain responses to each image.
The people who’d successfully kept weight off responded differently to the food images, with strong signals in the left superior frontal region and right middle temporal region of the brain – a pattern consistent with greater inhibitory control.
“It is possible that these brain responses may lead to preventive or corrective behaviors – particularly greater regulation of eating – that promote long-term weight control,” said McCaffery, who is also an assistant professor of psychiatry and human behavior at the Warren Alpert Medical School of Brown University. “However, future research is needed to determine whether these responses are inherent within an individual or if they can be changed.”
The study was funded by a grant from the National Institutes of Health.

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