Weight loss success linked to high-level brain functions, study finds

New research from the Montreal Neurological Institute and Hospital in Canada suggests that your brain — specifically its regions responsible for self-control — play a significant role in weight loss.

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"That area of the brain has the ability to take into account long-term information, such as the desire to be healthy, in order to control immediate desires," study author Alain Dagher said in a news release.

For the study, recently published the journal Cell Metabolism, researchers examined 24 subjects from a weight loss clinic, all of whom underwent a functional MRI study of the brain that assessed brain regions like the lateral prefrontal cortex and ventral medial prefrontal cortex. The first has been linked to self-control, whereas the latter is known to be involved in motivation, value and desire.

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They assessed the role of two hormones, leptin and ghrelin, known to increase likeliness of eating while losing weight. Most people who lose weight, Dagher said, experience a change in both hormones. But “some people, for reasons we do not know, are able to maintain their self-regulation in the face of that signal.”

The 25 subjects were shown images of appetizing foods or control pictures of scenery at baseline, the one-month mark and the three-month mark. According to researchers, showing the appetizing foods made the ventral medial prefrontal cortex area (linked to motivation, value and desire) more active. As the study went on, that signal dimmed in people who were most successful at weight loss, and the lateral prefrontal cortex signal (linked to self-control) increased.

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“In this study, leptin and ghrelin adaptations to weight loss did not explain why diets are unsustainable in the long term,” authors wrote. “Our results are not consistent with the suggestion that reduced leptin levels during energy restriction might promote increased food intake and contribute to the weight-loss plateau or weight regain.”

But, Dagher said, "these results suggest that weight loss treatments that increase self-control, such as cognitive behavioral therapy, may be helpful, particularly when stress is involved in leading to overeating. Stress disrupts the lateral prefrontal cortex control mechanism, but you may be able train people to seek a different strategy."

There are multiple limitations with the study, however. For one, the sample size is quite small and limited statistical power, though researchers note it is “common for within-design neuroimaging studies.” They also point out that there was only one male participant, so the results “are only applicable to females.”

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Researchers also did not test for hormonal resistance and lacked a control group.

"Further studies are justified, and could include larger cohorts, a control group, monitoring of daily food intake and activity, indirect calorimetry, more precise estimation of insulin sensitivity, and additional known modulators of food intake and activity," they wrote.

But despite the limitations, authors are confident that their results are consistent with a model that suggests decision-making and self-control are at the center of human weight control.

Read the full study at sciencedirect.com.

Cox Media Group