© CAB International 2020. Many human studies have reported controversial results on the benefit of probiotics on leptin levels. White adipose tissue (WAT) secretes leptin and plays an important role in energy balance and glucose homeostasis by decreasing food consumption and acting on fatty acid oxidation and weight reduction. Evidence on probiotics suggests that supplementation may have beneficial effects on lipid metabolism and leptin levels by altering the gut microbiota. However, most of the recent data have shown opposite results.