Recent studies have shown the presence of functional brown adipose tissue (BAT) in adult humans in glucose and energy metabolism. This short study by Chondronikola et al published in Cell Metabolism 1 shows that during prolonged non-shivering cold exposure in obese/overweight individuals, brown adipose tissue is activated. This is associated with increased lipolysis, increased free fatty acid (FFA) oxidation and cycling. These changes in the BAT also affect insulin sensitivity in the white adipose tissue. This study provides insight into an unexplored role of function of BAT in lipid metabolism during prolonged cold exposure.