Effect of weight loss and regional fat distribution on plasma leptin concentration in obese women

OBJECTIVES: To investigate how circulating leptin concentrations are relate d to regional fat distribution and whether moderate weight loss alters thes e relationships. DESIGN: A 6 month, clinical weight reduction trial with measurements before and after weight loss. SUBJECTS: 38 healthy, obese women (age: 44.3 +/- 9.9 y, BMI: 34.0 +/- 4.0 k g/m(2)). MEASUREMENTS: The following measurements were made. 1. indices of obesity a nd fat distribution: weight, body mass index (MI), hip circumference (perip heral fat), waist circumference, total body fat (bioelectrical impedance), abdominal fat distribution: visceral fat and abdominal subcutaneous fat (ul trasonography); and 2. Biochemical measurements: plasma leptin and serum in sulin. RESULTS: Baseline plasma leptin concentrations were three-fold higher in ob ese women than in normal weight controls. After weight loss averaging 8.4 k g (9.0 %), plasma leptin decreased by a mean of 22.3 % (P < 0.001), corresp onding to body fat decrease of 16.6% (P < 0.001), abdominal subcutaneous fa t decrease of 17.4% (P < 0.001) and visceral fat decrease of 18.7% (P < 0.0 01). The total amount of body fat correlated with plasma (serum) leptin bef ore (r = 0.64, P < 0.001) and after (r = 0.75, P < 0.001) weight loss. Plas ma leptin concentrations expressed per kg of body fat did not change signif icantly during weight loss. After controlling for body fat, baseline leptin concentrations were significantly associated with hip circumference (r = 0 .57, P < 0.001) but not with any indices of abdominal fat distribution. Aft er weight loss the associations became significant for hip and waist circum ference as well as for visceral and abdominal subcutaneous fat. Changes in leptin correlated with changes in all indices of obesity except visceral fa t. CONCLUSIONS: Plasma leptin concentrations reflect not only total fat mass b ut also adipose tissue distribution, especially peripheral fat. Plasma lept in values per kilogram of fat mass do not change significantly with modest weight loss.