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Post-bariatric surgery exercise modulates brain regions associated with regulation of food intake

Patients who exercise after bariatric surgery produced functional alterations in brain networks associated with food intake and modified by obesity. The study’s researchers said the findings confirm the hypothesis that exercise and bariatric surgery act synergistically on the connectivity among brain regions associated with cognition, reward and emotional regulation, potentially moderating hunger and enhancing satiety.

Figure 1: Hypothalamic connectivity: red indicates increase in brain connectivity after intervention, black indicates decrease, beige indicates no change. Panel on left shows areas investigated, with right medial hypothalamus highlighted in red because it changed after post-bariatric exercise. Panel on right shows increased connectivity between sensory and visual areas and right medial hypothalamus, including supramarginal gyrus and temporal regions. (Credit: Carlos Merege Filho)

"The regulation of energy expenditure is governed by multiple internal and external signals. People with obesity display major dysregulation of brain regions associated with appetite and satiety. Our study showed that exercise by post-bariatric patients helped 'normalize' these complex networks so as to improve the central control of food intake” said Professor Bruno Gualano, from the Hospital das Clínicas (HC), University of São Paulo's Medical School (FM-USP) in Brazil, and co-author of the paper, ‘Exercise modifies hypothalamic connectivity and brain functional networks in women after bariatric surgery: a randomized clinical trial’, published in the International Journal of Obesity. “For example, some of these regions are activated and connect more intensely in people with obesity when they eat fatty or sugary food, increasing their desire to consume such food. We found that exercise counteracts this effect, at least in part.”

They noted that exercise increased the connectivity between the hypothalamus (the brain region that controls homeostasis, including regulation of appetite and energy expenditure) and the brain's sensory areas. At the same time, it apparently decreased the link between the default mode network, which is more active during a resting state, and the salience network, the brain region involved in decision-making. The researchers also found that exercise after bariatric surgery appeared to modulate the medial hypothalamic nucleus involved in appetite suppression and increased energy expenditure.

From the clinical standpoint, Gualano believes the findings suggest that exercise should be considered an important complementary therapy to improve brain functions and enhance the known benefits of bariatric surgery, such as a reduction in cardiometabolic risk factors, as well as preservation of muscle mass and bone health.

The randomised clinical trial involved 30 women aged between 18 and 60 who had a Roux-en-Y gastric bypass. Half the study sample were randomly assigned to a six-month exercise programme of resistance and aerobic training three times a week, starting three months after the operation and supervised by a team of physical education professionals.

Clinical, laboratory and brain functional connectivity parameters were assessed at the start of the trial, as a baseline, and again three and nine months after the operation. Functional magnetic resonance imaging (fMRI) was used to detect connectivity between anatomically distinct brain areas organized as networks, and to analyse the combined effects of the surgical procedure and exercise training. Data collection began in June 2018 and ended in August 2021.

"The literature has already shown that post-bariatric patients have many brain alterations compatible with improved control of appetite, satiety and hunger in neural circuits that govern food intake. Our study found that exercise training bolstered this response," added Gualano, noting the importance of lifestyle changes to maintain the benefits of weight loss for people with obesity. "Regular exercise is known to induce several physiological adaptations that translate into health benefits. These benefits are reversed if the patient stops exercising regularly. Our study didn't measure the duration of the brain changes induced by exercise, however. They're highly likely to diminish and possibly even go into reverse as the amount and intensity of exercise decrease. It's crucial to adopt a healthy lifestyle in order for the responses to bariatric surgery to be long-lasting.”

Next steps for the research group will include studying the effects in people with obesity of exercise and diet combined with other weight loss strategies, including new drugs such as peptide analogs or incretin mimetics, a class of medications commonly used to treat type 2 diabetes. Incretins are gut hormones that aid digestion and blood sugar control by signalling to the brain to stop eating after a meal.

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