The influence of short-term fasting on serum leptin levels, and selected hormonal and metabolic parameters in morbidly obese and lean females

The aim of our study was to compare the changes of serum leptin levels afte r 24-h fasting in morbidly obese and lean females and to search for hormona l and metabolic factors responsible for the changes in serum leptin levels. Fourteen morbidly obese and twelve lean females were included in the study. The blood for leptin, insulin, cortisol, blood glucose (BG), beta -OH-buty rate (beta -OH), dehydroepiandrosterone (DHEA) and DHEA-sulphate (DHEA-S) m easurements was withdrawn before and after a 24-h fast. Basal body mass index (BMI), serum leptin, insulin and beta -OH levels were significantly higher in the obese compared to the lean group. The 24-h fas ting decreased significantly BMI, serum leptin (by 20% in obese vs. 62% in lean subjects), insulin (by 23.3% in obese vs. 23.1% in lean subjects) and increased beta -OH (by 36% in obese vs. 1300% in lean subjects). Basal seru m leptin levels correlated positively with BMI in both groups and with insu lin levels in the obese group. The multiple regression analysis using Delta leptin as dependent and the basal values of the rest of studied parameters as independent variables revealed that in lean subjects serum cortisol tog ether with DHEA-S and BMI accounted for 71% of variations of the change of serum leptin levels (Delta leptin = 0.31 - 0.0101 cortisol + 0.0012 DHEA-S + 0.37 BMI). In obese subjects the 43.9% of variations of the change of ser um leptin levels was explained by BMI together with age and DHEA-S levels ( Delta leptin = 36.09 + 0.35 BMI - 0.717 age - 0.008 DHEA-S). The drop of serum leptin levels after 24-h starvation is significantly blun ted in obese compared to lean subjects. The reason for the difference is pr obably the insulin resistance possibly further modified by different DHEA-S levels.