Low-calorie diet-induced weight loss is associated with altered brain connectivity and food desire in obesity

Objective: The main objective of this study is to better understand the effects of diet-induced weight loss on brain connectivity in response to changes in glucose levels in individuals with obesity. Methods: A total of 25 individuals with obesity, among whom 9 had a diagnosis of type 2 diabetes, underwent functional magnetic resonance imaging (fMRI) scans before and after an 8-week low-calorie diet. We used a two-step hypereuglycemia clamp approach to mimic the changes in glucose levels observed in the postprandial period in combination with task-mediated fMRI intrinsic connectivity distribution (ICD) analysis. Results: After the diet, participants lost an average of 3.3% body weight. Diet-induced weight loss led to a decrease in leptin levels, an increase in hunger and food intake, and greater brain connectivity in the parahippocampus, right hippocampus, and temporal cortex (limbic–temporal network). Group differences (with vs. without type 2 diabetes) were noted in several brain networks. Connectivity in the limbic–temporal and frontal–parietal brain clusters inversely correlated with hunger. Conclusions: A short-term low-calorie diet led to a multifaceted body response in patients with obesity, with an increase in connectivity in the limbic–temporal network (emotion and memory) and hormone and eating behavior changes that may be important for recovering the weight lost.