Association of body mass and body fat distribution with serum melatonin levels in obese women either non-operated or after jejunoileostomy.

The association of body mass index (BMI) and body fat distribution (as measured by waist-to-hip circumference ratio; WHR) with serum melatonin (MEL) levels determined at 02 and 14 h were examined in 22 non-operated obese women and 21 obese women who underwent jejunoileostomy for morbid obesity 2 to 6 years earlier as well as in 20 gender and age-matched healthy controls with normal body weight. All non-operated obese women either with moderate or morbid obesity had significantly higher MEL concentration at 14 h compared with controls, whereas the amount of MEL secreted at 02 h was elevated only in morbidly obese women. The mean differences between serum MEL levels at 14 h and 02 h (delta MEL) was reduced in morbidly obese women - it may be due to desynchronisation of its circadian rhythmicity. Among women who underwent jejunoileostomy for morbid obesity the values of MEL were normalized only in those with a noted body mass reduction and with BMI and WHR indexes less than 28 kg/m² and 0.83, respectively. MEL correlated positively with BMI and WHR indexes at 14 h in all subjects studied. Negative correlation was noted between the relative values of delta MEL and BMI in both non-operated and operated obese women with BMI indexes >31 kg/m².