Leptin, thyrotropin, and thyroid hormones in obese/overweight women before and after two levels of energy deficit

Abstract

The aim of our study was to compare serum concentration of leptin and pituitary-thyroid axis hormones in obese/overweight women before and after two levels of energy deficit with those parameters in lean women on adequate energy intake. Additionally, we attempted to elucidate if the effect of weight reduction could be related to anthropometric and hormonal parameters before treatment. Anthropometric and hormonal parameters-serum leptin, TSH, T4, fT4, T3 and leptin to fat mass (Lep/fm), T3/T4, fT4/T4, T4/TSH, fT4/TSH--were compared in two groups of women (n =18 each)--lean women (C: BMI 22.0 +/- 1.2) and overweight/obese (Ov/Ob: BMI 29.9 +/- 3.3). Ov/Ob women were subjected to weight-reducing treatment consisting of energy intake equal to 80% of calculated total energy expenditure for the first 4 wk and to 50% for subsequent 4 wk. All baseline hormone concentrations, Lep/fm, and fT4/T4 were higher in overweight/obese group. After 20% energy deficit decrease in BMI, percent body fat (fm%), leptin, T3, and TSH serum concentrations as well as in Lep/fm and T3/T4 was observed; T4/TSH increased, fT4, fT4/T4 and fT4/TSH did not change significantly. Increase in energy deficit from 20% to 50% resulted in normalization of Lep/fm, on the other hand, it provoked greater decline in thyroid hormone plasma concentration, which could hinder further mass reduction. Leptin and TSH levels were positively correlated after 50% energy deficit treatment. Changes in fm% were directly related to baseline T4/TSH, fT4/TSH, and log TSH. In conclusion, TSH serum concentration and its ratio to T4 and fT4 before weight reduction could be a good predictor of successful weight loss.