Can your body weight dull your brain impulses to food even when you begin to lose it? What does a new study say?

Obesity affects the brain’s reward system leading to reduced sensitivity to the satisfying effects of food. As a result, those with obesity may require larger amounts of food to experience the same level of satisfaction, making it harder to adhere to calorie-restricted diets, say neurologists

weight managementObesity has been found to have a profound impact on the functioning of the brain, potentially impeding weight loss efforts. (Pic source: Freepik)

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Obesity may blunt the brain’s ability to process signals of feeling full and satiety to such an extent that even if you try to lose weight, you would still be drawn to foods rich in sugars and fats and not know where to stop, a new study suggests.

A new study by the Yale School of Medicine has found that people with obesity had a diminished ability to respond to these signals. For the study, researchers used feeding tubes to send sugars or fats directly into participants’ stomachs and used functional magnetic resonance imaging to assess the brain’s chemical responses to these foods. Among the people with lower BMIs, infusions of sugars and fats produced reduced activity in several regions of the brain involved in hunger regulation, the study found. But scientists didn’t detect any brain response to these nutrients in obese people. Moreover, when they asked obese participants to lose weight over 12 weeks, the brain’s lack of response to sugars and fats remained constant.

“Obesity has been found to have a profound impact on the functioning of the brain, potentially impeding weight loss efforts. Research suggests that the brains of individuals with obesity undergo structural and functional changes that contribute to difficulties in losing weight and maintaining a healthy body mass.

One key finding is that obesity affects the reward and pleasure centres of the brain, leading to an increased desire for high-calorie foods. The brain’s response to food cues becomes amplified, making it harder for individuals with obesity to resist cravings and make healthy dietary choices,” says Dr P N Renjen, Senior Consultant, Neurology, Indraprastha Apollo Hospitals, Delhi.

“Furthermore, obesity is associated with alterations in the brain’s regulation of appetite and satiety signals. Hormones such as leptin, which help regulate hunger and metabolism, may become less effective in individuals with obesity. This can lead to a perpetual cycle of overeating and difficulty feeling full, further exacerbating weight management challenges. Moreover, studies indicate that obesity is linked to inflammation in the brain, which can negatively impact cognitive functions and hinder decision-making abilities related to food choices and self-control,” he explains.

Interpreting the new research, Dr Vipul Gupta, Director – Neurointervention and stroke unit Artemis-Agrim Institute of Neurosciences, Artemis Hospital, Gurugram, says, “One key area of interest is the brain’s reward system, particularly the mesolimbic dopamine pathway. This pathway is involved in the sensation of pleasure and reward, including food-related rewards. Research suggests that obesity may alter the functioning of this pathway, leading to reduced sensitivity to the rewarding effects of food. As a result, individuals with obesity may require larger amounts of food to experience the same level of satisfaction, making it harder to adhere to calorie-restricted diets.”

Obesity is often linked to emotional eating and an increased susceptibility to stress-related eating. “The brain’s response to stress involves the release of cortisol, a hormone that can stimulate appetite and promote the consumption of calorie-dense foods. Chronic stress and emotional disturbances associated with obesity may create a vicious cycle, further hindering weight loss efforts,” says he.

So what does this research mean for traditional weight loss strategies that predominantly focus on caloric restriction and increased physical activity? “These approaches may overlook the underlying neurological factors that make weight loss challenging for individuals with obesity. The altered reward system in the brains of individuals with obesity can lead to decreased feelings of fullness and increased cravings for high-calorie foods. This can make it difficult to stick to a calorie-restricted diet and maintain long-term weight loss. Leptin resistance and disrupted energy balance can contribute to a slower metabolic rate in individuals with obesity. This means that their bodies may burn fewer calories at rest, making weight loss even more challenging. The emotional and stress-related aspects of obesity can negatively impact mental well-being and self-regulation. These psychological barriers can further impede weight loss efforts, as individuals may turn to food as a coping mechanism or struggle to maintain motivation,” says Dr Gupta.

That’s why understanding the impact of obesity on the brain is crucial for developing effective weight loss strategies. “By addressing the neurological changes associated with obesity, researchers and healthcare professionals can develop targeted interventions to help individuals overcome the physiological barriers to weight loss and improve overall health outcomes,” Dr Renjen says.

First published on: 26-06-2023 at 13:22 IST

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