Diet-induced weight loss tied to altered brain connectivity, hunger in people with obesity

Individuals with obesity who underwent a short-term, low-calorie diet demonstrate a multifaceted body response, including an increased brain connectivity in the limbic‒temporal network (emotion and memory) as well as hormone and eating behaviour changes that seem relevant for recovering the weight lost, a recent study has shown.

The authors carried out this study to improve their understanding of the effects of diet-induced weight loss on brain connectivity in response to changes in glucose levels in those with obesity.

Twenty-five individuals with obesity participated in this study, of whom nine had been diagnosed with type 2 diabetes (T2D). Participants underwent functional magnetic resonance imaging (fMRI) scans before and after an 8-week low-calorie diet.

A two-step hypereuglycaemia clamp approach was used to simulate the changes in glucose levels seen in the postprandial period. This was combined with a task-mediated fMRI intrinsic connectivity distribution (ICD) analysis.

After the short-term, low-calorie diet, participants lost an average of 3.3 percent of body weight. This diet-driven weight loss resulted in a reduction in leptin levels, an increase in hunger and food intake, and heightened brain connectivity in the parahippocampus, right hippocampus, and temporal cortex (limbic-temporal network).

Differences were also observed in several brain networks between patients with and without T2D. Notably, connectivity in the limbic‒temporal and frontal‒parietal brain clusters showed an inverse association with hunger.