Recent studies have shown the presence of functional brown adipose tissue (BAT) in adult humans and it role in thermogenesis. This study by Blondin et al published in Cell Metabolism shows that similar to rodents; adult human brown adipose tissue uses lipids as its cellular fuel during thermogenesis. Inhibition of triglyceride lipolysis was associated with a shift in the skeletal muscle mediated shivering instead and a shift in fuel utilization from lipids to glucose. This study provides yet another confirmatory role of a functional brown fat in adult humans that is fueled by fatty acids.