Study: fMRI shows link to weight maintenance, brains response to food

A difference in brain activity patterns may explain why some people are able to maintain a significant weight loss while others regain the weight, according to a functional MRI (fMRI) study published last month in the American Journal of Clinical Nutrition.

Research has indicated that “successful weight-loss maintainers” work harder than people of normal weight to maintain their weight loss, including restricting fat in diets and achieving higher physical activity levels, according to the authors. They noted, however, that prior to this study, little research to date has examined how “successful weight-loss maintainers” differ biologically from normal-weight and obese controls.

Jeanne M. McCaffery, PhD, from the Weight Control and Diabetes Research Center at Miriam Hospital in Providence, R.I., and colleagues reported that when individuals who have kept the weight off for several years were shown pictures of food, they were more likely to engage the areas of the brain associated with behavioral control and visual attention, compared with obese and normal weight participants.

“Our findings shed some light on the biological factors that may contribute to weight loss maintenance. They also 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 McCaffery.

The researchers used fMRI to study the brain activity of three groups: 18 individuals of normal weight, 16 obese individuals (defined as having a body mass index of at least 30) and 17 participants who have lost at least 30 lbs and have successfully maintained that weight loss for a minimum of three years.

After a four-hour fast, they were shown pictures of food items, including low-calorie foods (such as whole grain cereals, salads, fresh vegetables and fruit); high-calorie foods (including cheeseburgers, hot dogs, French fries, ice cream, cake and cookies), and nonfood objects with similar visual complexity, texture and color (such as rocks, shrubs, bricks, trees and flowers). The fMRI scan documented brain responses to each image.

Those in the successful weight loss maintenance group responded differently to the pictures compared with the other groups. Specifically, investigators observed strong signals in the left superior frontal region and right middle temporal region of the brain—a pattern consistent with greater inhibitory control in response to food images and greater visual attention to food cues.

“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 at Brown University in Providence. “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 (NIH).

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