Increase in brown adipose tissue activity after weight loss in morbidly obese subjects.

Context: Stimulation of thermogenesis in brown adipose tissue (BAT) is a potential target to treat obesity. We earlier demonstrated that BAT activity is relatively low in obese subjects. It is unknown whether BAT can be recruited in adult humans.

Objective: To study the dynamics of BAT, we observed BAT activity in morbidly obese subjects before and after weight loss induced by bariatric surgery.

Design: This was an observational prospective cohort study.

Setting: The study was conducted at a referral center.

Patients: Ten morbidly obese subjects eligible for laparoscopic adjustable gastric banding surgery were studied before and 1 yr after bariatric surgery.

Main Outcome Measure: The main outcome measure was BAT activity, as determined after acute cold stimulation using (18)F-fluorodeoxyglucose positron emission tomography and computed tomography.

Results: Before surgery, only two of 10 subjects showed active BAT. One year after surgery, the number of subjects with active BAT was increased to five. After weight loss, BAT-positive subjects had significantly higher nonshivering thermogenesis compared with BAT-negative subjects (P < 0.05).

Conclusions: The results show that in humans BAT can be recruited in the regions in which it was also reported in lean subjects before. These results for the first time show recruitment of BAT in humans and may open the door for BAT-targeted treatments of obesity.