Recruited brown adipose tissue as an antiobesity agent in humans

TLDR

Brown adipose tissue burns fat to generate heat during cold exposure and is implicated in energy metabolism, suggesting that its recruitment could aid in reducing body fat. The study examined whether repeated cold exposure and daily capsinoid ingestion could stimulate BAT activity and energy expenditure in healthy adults with low baseline BAT. Participants underwent repeated 2‑hour cold sessions and daily capsinoid intake, and researchers measured changes in BAT activity, energy expenditure, and body fat over a 6‑week period. The interventions increased energy expenditure and BAT activity, with the 6‑week cold protocol also reducing body fat, and the degree of BAT activation was inversely correlated with fat mass, confirming that BAT can be recruited to lower adiposity even in individuals with initially low BAT activity.

Abstract

Brown adipose tissue (BAT) burns fat to produce heat when the body is exposed to cold and plays a role in energy metabolism. Using fluorodeoxyglucose-positron emission tomography and computed tomography, we previously reported that BAT decreases with age and thereby accelerates age-related accumulation of body fat in humans. Thus, the recruitment of BAT may be effective for body fat reduction. In this study, we examined the effects of repeated stimulation by cold and capsinoids (nonpungent capsaicin analogs) in healthy human subjects with low BAT activity. Acute cold exposure at 19°C for 2 hours increased energy expenditure (EE). Cold-induced increments of EE (CIT) strongly correlated with BAT activity independently of age and fat-free mass. Daily 2-hour cold exposure at 17°C for 6 weeks resulted in a parallel increase in BAT activity and CIT and a concomitant decrease in body fat mass. Changes in BAT activity and body fat mass were negatively correlated. Similarly, daily ingestion of capsinoids for 6 weeks increased CIT. These results demonstrate that human BAT can be recruited even in individuals with decreased BAT activity, thereby contributing to body fat reduction.