Obesity strains the brain, impairs nutritional response and interferes with eating habits

A study in human volunteers led by researchers at the UMC Amsterdam and Yale University found that obese people have a reduced brain response to certain nutrients that doesn’t improve after weight loss. The overall findings may partly explain why so many people lose weight despite successful dieting.

“Our findings show that long-term brain adaptations occur in obese people that can influence eating behavior,” said Mireille Seruri, M.D., Ph.D., professor of endocrinology at UMC Amsterdam and lead researcher. suggesting,” he said. “We found that obese people had less dopamine release in areas of the brain important for motivating food intake compared to healthy weight people. Obese subjects also showed reduced responsiveness of brain activity to gastric nutrient infusions.Together, these findings suggest that obese individuals may have impaired gastric and/or intestinal nutrient sensing and/or nutritional Signal perception is reduced, suggesting that this may have a significant impact on food intake … The fact that these brain responses do not recover after weight loss may explain why most Do people gain weight back after the first successful weight loss?

Serlie and colleagues reported their findings in the following paper. natural metabolismIn an article titledIn obese humans, brain responses to nutrients are severely impaired and not restored by weight loss: a randomized crossover study.In it, the researchers concluded, “impaired neuronal responses to nutrient signals may contribute to overeating and obesity, and continued resistance to nutritive signals after ingestion after significant weight loss may contribute to weight loss.” It may partly explain the higher rate of weight recovery after success.”

Food intake depends on the integration of complex metabolic and neural signals between the brain and several organs such as gut and nutrient signals in the blood. “…There is increasing evidence that signals that occur after food intake, so-called post-nutrition signals, play a powerful role in regulating eating behaviour,” the authors noted. This network causes hunger and satiety and regulates food intake and food-seeking motivation. However, while these processes are becoming increasingly well understood in animals, including in the context of metabolic diseases such as obesity, little is known about what happens in humans. “Despite these interesting, mostly preclinical, studies, little is known about the role of post-feeding nutrient signals in human physiology and the progression of obesity,” the researchers continued. This is partly due to the difficulty in designing setups to reveal these mechanisms in the clinic.

To address this knowledge gap, Surley, a professor at Yale University, and colleagues at both universities designed a controlled trial. In this study, 30 healthy-weight and 30 obese participants were injected with specific nutrients directly into their stomachs, while MRI was used to measure brain activity, and SPECT scans were used to measure dopamine release. was measured. “…we hypothesized that intragastric infusion of glucose and lipids modulates brain neuron activity and striatal dopamine release in lean humans, and that these responses are impaired in obese humans,” said the researchers. said. Obese participants were studied both before and after a dietary intervention aimed at reducing body weight by 10%. “…we hypothesized that the impaired response to post-ingestion nutrient signals was partially reversed by diet-induced weight loss,” the researchers added.

Results showed that healthy-weight participants exhibited specific patterns of brain activity and dopamine release after nutrient infusion, whereas these responses were significantly blunted in obese participants. Furthermore, 10% weight loss (after 12 weeks of dieting) was insufficient to restore brain responses in obese patients, and long-term brain adaptation occurred in the setting of obesity to achieve weight loss. It is suggested that it persists. “Together, these observations provide insight into the physiology of human eating behavior and the pathophysiology of obesity,” the researchers said.

The researchers suggest that glucose and lipids differentially affect brain regions involved in regulating feeding behavior via post-ingestion signaling, suggesting that impairment of post-ingestion nutrient signaling is pathological. It supports the hypothesis that it may contribute to unhealthy eating behavior, overeating and obesity. The persistence of these changes after dietary weight loss may contribute to the high rate of weight regain after dietary intervention. “The lack of reversibility after significant weight loss suggests that the higher rate of weight regain after successful weight loss is partly explained by continued resistance to post-feeding nutritional signals.” researchers write.

write on accessories news and viewsDr. Mary Elizabeth Boe and Dr. Alexandra G. Diferiantonio of the Flanlin Biomedical Institute at VTC in Roanoke said that the reported study investigated the effects after ingesting carbohydrates and lipids alone, and that more to produce post-ingestion effects of A full understanding of gut-brain signaling will require future studies to investigate post-ingestion effects of protein. Nevertheless, the researchers write: “Given that weight regain after behavioral weight loss is ubiquitous, this study is a good starting point for future research exploring how signaling in the gut-brain axis influences weight loss maintenance and weight regain.” It also provides a fertile basis for the differential nutrient-induced responses in responders and non-responders to clinical weight loss treatments is an important research tool. ”