Brown Adipose Tissue Volume and Fat Content are Positively A
Human brown adipose tissue (BAT) volume has been consistently claimed as inversely associated with whole-body adiposity. However, recent advances in the assessment of human BAT suggest that previously reported associations may have been biased.

The present cross-sectional study investigates the association of BAT volume, mean radiodensity, and 18F-fluordeoxyglucose (18F-FDG) uptake (assessed via a static positron emission tomography-computerized tomography (PET-CT) scan after a 2-hour personalized cold exposure) with whole-body adiposity (measured by dual-energy X-ray absorptiometry) in 126 young adults (42 men/84 women; 25±5 kg/m2).

BAT volume, but not 18F-FDG uptake, was positively associated with body mass index (BMI), fat mass, and visceral adipose tissue mass in men, but not in women. These associations were independent of the date when the PET-CT was performed, insulin sensitivity and body surface area. BAT mean radiodensity, an inverse proxy of BAT fat content, was negatively associated was with BMI, waist circumference, fat mass and visceral adipose tissue mas in men and with percentage fat mass in women.

These results refute the widely held belief that human BAT volume is reduced in obese persons, at least in young adults, and suggest that it might even be the opposite in young men.