Brown Adipose Tissue Modulates Insulin Sensitivity in Humans

In rodents, brown adipose tissue (BAT) regulates cold-and diet-induced thermogenesis (CIT; DIT). Whether BAT recruitment is reversible and how it impacts on energy metabolism have not been investigated in humans. We examined the effects of temperature acclimation on BAT, energy balance, and substrate metabolism in a prospective crossover study of 4-month duration, consisting of four consecutive blocks of 1-month over-night temperature acclimation (24°C [month 1] → 19°C [month 2] → 24°C [month 3] → 27°C [month 4]) of five healthy men in a temperature-controlled research facil-ity. Sequential monthly acclimation modulated BAT re-versibly, boosting and suppressing its abundance and activity in mild cold and warm conditions (P < 0.05), re-spectively, independent of seasonal fluctuations (P &lt