A recent study by Amsterdam UMC and Yale University, published in Nature Metabolism, reveals that individuals with obesity exhibit reduced brain responses to certain nutrients. Furthermore, the study suggests that these diminished responses do not improve after weight loss.

Obese individuals undergo lasting changes in the brain

According to Professor Mireille Serlie, lead researcher at Amsterdam UMC, individuals with obesity undergo significant and enduring changes in the brain that can impact their eating behavior. The study revealed that people with obesity exhibit lower levels of dopamine release in a specific brain region associated with the motivation to consume food, in contrast to individuals of healthy body weight. Dopamine plays a crucial role in generating pleasurable sensations related to food consumption.

The regulation of food intake involves intricate interactions between the brain, gut, and blood signals. This network controls hunger and satiety sensations, manages food intake, and influences the motivation to seek food.

Although there is a growing understanding of these processes in animals, particularly regarding metabolic disorders like obesity, there is limited knowledge of the corresponding mechanisms in humans. This is partly because it is challenging to create experimental conditions in clinical settings that can provide insights into these mechanisms.

Dopamine release is suppressed in obese individuals.

Professor Serlie from Yale University and colleagues conducted a controlled trial to address the knowledge gap. The trial involved infusing targeted nutrients into the stomachs of 30 subjects with obesity and an equal number of healthy body weight individuals. Brain activity was measured using MRI scans, and dopamine release was assessed using SPECT scans.

Brain activity and dopamine release in response to nutrient infusion were found to be significantly reduced in individuals with obesity compared to those with healthy body weights. Even after a 10% weight loss through a 12-week diet, these brain responses did not return to normal in obese individuals, indicating that long-term changes in the brain occur in the context of obesity and persist even after weight loss. This may help explain why many people regain weight after successful weight loss efforts.