Effects of mild aerobic exercise and a mild hypocaloric diet on plasma leptin in sedentary women

1. The present study was conducted to investigate whether mild aerobic exer cise and a mild hypocaloric diet, instead of severe restrictions on caloric intake, would affect weight reduction and plasma leptin concentrations. 2. Forty-one middle-aged sedentary women (15 obese and 26 non-obese) partic ipated in a 12 week lifestyle-modification programme to reduce cardiovascul ar risk factors, Bodyweight, body composition, plasma leptin concentrations , serum lipid profiles, fasting plasma glucose and fasting plasma insulin w ere measured before and after the 12 week intervention. The intervention co nsisted of aerobic exercise, corresponding to approximately 50% of maximal oxygen consumption, and personal diet counselling. 3. Bodyweight decreased by (mean+/-SD) 3.9+/-3.4 kg in the obese group (P < 0.05) and by 1.7+/-1.8 kg in the non-obese group (P < 0.05), The plasma le ptin concentration decreased significantly from 14.7+/-5.3 to 8.9+/-3.6 ng/ mL in the obese group (P < 0.001) and from 7.6+/-3.9 to 5.6+/-2.2 ng/mL in the non-obese group (P < 0.01). 4. Overall, for all subjects, both pre- and postintervention, the plasma le ptin concentration was significantly correlated with body mass index (BMI; pre-intervention: r = 0.73, P < 0.0001; postintervention: r = 0.67, P < 0.0 001), fat mass (FM; preintervention: r = 0.74, P < 0.0001; postintervention : r = 0.63, P < 0.0001) and fasting plasma insulin (pre-intervention: r = 0 .66, P < 0.001; postintervention: r = 0.45, P < 0.01). The change in plasma leptin concentration was significantly correlated with the respective chan ges in BMI (r = 0.64, P < 0.0001), FM (r = 0.48, P < 0.01) and fasting plas ma insulin (r = 0.58, P < 0.0001). Interestingly, the ratio of plasma lepti n concentration to BMI or FM diminished significantly after intervention. I n addition, we found that the plasma leptin concentration decreased in part icipants whose FM did not decrease. These results suggest that the producti on of leptin per unit FM decreased after intervention. 5. Mild aerobic exercise and a mild hypocaloric intake decreased body mass and the plasma leptin level in Japanese middle-aged sedentary women, This d ecrease in plasma leptin levels was likely to be associated with weight red uction plus some unknown factor(s).