Physiology of Weight Regain after Weight Loss: Latest Insights.

Purpose of review: This review summarizes the most recent research on the physiology of weight regain. It describes developments in areas that are currently being addressed and that may indicate promising directions for future research.

Recent findings: Weight regain occurs independent of the way prior weight loss is achieved, i.e. by lifestyle, surgery or pharmacotherapy. Recent novel findings regarding weight regain belong to four areas. First, the immune obesity memory of which besides persistent immune cells promoting weight regain cells have been found that reduce weight regain. Second, the gut microbiome where autologous transplantation can limit weight regain. Third, the composition of the weight loss with the percentage of lost fat-free mass being inverse to the amount of regained weight independent of the weight loss procedure. Fourth, appetite control where after weight loss altered hypothalamic activity promoting hunger and weight regain persists, possibly mediated by altered neurotensin responses. In all four areas more conclusive evidence for their role in weight regain still needs to be obtained. Most studies on physiological mechanisms of weight regain are associative in nature and the number of intervention studies is very limited. To bring the field further, carefully designed intervention studies taking into account the dynamic character of weight loss and weight regain are needed.