Editors' ChoiceMetabolism

The brain carries a lot of weight

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Science Translational Medicine  12 Dec 2018:
Vol. 10, Issue 471, eaaw0524
DOI: 10.1126/scitranslmed.aaw0524

Abstract

Researchers used neuroimaging to show that the best predictor of successful weight loss was greater brain activity in prefrontal areas in the brain involved in self-control.

About 45 million Americans undertake weight-loss diets every year but keeping the pounds off long-term proves to be a major challenge. To help understand why, Neseliler et al. studied the effects of a weight-loss diet on brain activity and blood levels of hormones that regulate appetite. They hypothesized that weight loss would cause adaptations in appetite hormones that would override self-control of food intake.

Twenty-four overweight/obese adults were recruited from a weight loss clinic and studied before and one and three months after starting the 1200 calorie per day weight-loss diet. Study visits included functional magnetic resonance imaging (fMRI) scans to determine how their brain responded to pictures of appetizing foods compared with control pictures of scenery. Blood tests were performed to determine levels of hormones that help regulate appetite, including ghrelin and leptin. Body weight was obtained two years later in 19 of these participants to examine how brain activity related to long-term weight loss maintenance.

People who achieved greater weight loss after one and three months of dieting and kept the weight off two years later showed higher activity in prefrontal brain regions involved in self-control. As expected, ghrelin increased, and leptin decreased when the participants lost weight. However, changes in these appetite hormones did not counteract weight loss as the researchers had predicted. Instead, they found that greater reductions in leptin in response to weight loss correlated with further weight loss.

The study was limited by a small number of mostly female participants, and it did not include a control group of nondieters for comparison. In addition, body weight was obtained through self-report in a subset of participants at the two-year time point. Therefore, larger studies including both men and women, a control group, and more precise measures of body weight trajectories both before and after the weight loss program are warranted. Nevertheless, the research suggests that activation of prefrontal areas associated with self-control may play an important role in successful weight loss and in prevention of weight regain.

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