Plasma leptin in moderately obese men: independent effects of weight loss and aerobic exercise

The independent effects of weight loss and exercise on plasma leptin and to tal (AT), subcutaneous (SAT), and visceral (VAT) adipose tissue were invest igated in 52 obese men. Subjects were randomly assigned to four 12-wk proto cols: 1) control (C, n = 8), 2) diet-induced weight loss (DWL, n = 14), 3) exercise-induced weight loss (EWL, n = 14), and 4) exercise with weight mai ntenance (EWS, n = 16). Plasma leptin was unchanged in C (from 7.8 +/- 1.3 to 7.7 +/- 1.0 ng/ ml). Equivalent weight loss (7.5 kg) decreased leptin si gnificantly but similarly (DWL, from 8.5 +/- 1.0 to 4.8 +/- 0.6 ng/ ml; EWL , from 10.1 +/- 1.0 to 5.0 +/- 0.6 ng/ ml). Exercise in the absence of weig ht loss did not alter leptin levels (from 10.1 +/- 1.3 to 9.2 +/- 1.2 ng/ m l). Changes in leptin correlated with changes in AT and SAT (both P < 0.05) but not in VAT. We conclude that reduction in adipose tissue after weight loss results in a collateral decrease in circulating leptin, and exercise, independent of its effects on weight loss, has no profound influence on lep tin secretion.