RELATIONSHIP BETWEEN SEX STEROIDS AND BODY FAT IN OBESE GIRLS

Abstract

Obesity is associated with increased production rates of androgens and estrogens as well as with increased peripheral conversion of androgcns to estrogens. Aim of this study was to investigate the relationship between serum sex steroid concentrations and body fat distribution in 92 obese giils, age 15.1±0.7 (14.5-16.8) years, BM1 31.2± 4.5 (24.0-44.0) kg/m2, all PH 5. Waist and thigh girths were measured to determine the distribution of body fat. Girls were divided into three subgroups according to tertiles of their waist-to-thigh ratio (WTK). Girls with abdominal obesity (WTR>1.33)(O1) had higher levels of estradiol (E2)(82.4±28.3 vs 51.7±25.3 pg/mL), testosterone (T)(0.67± 0.22 vs 0.52±0.23ng/dL), androstenedione (2.02±0.52 vs 1.73±0.49μg/L), and DHEAS (4.22±1.52 vs 3.62±1.55mg/L) and lower levels of SHBG (6.66±4.23 vs 14.07±9.97ng/dL) than girls with glutcal-femoral obesity(O2)(all p<0.05, independent of BMI and % body fat). Interestingly, T/E2 was lower in O1 than in O2(p<0.01) suggesting increased aromatization of T to E2 in abdominal fat depots. In a linear regression analysis WTR correlated significantly with all the variables, BMI only with SHBG. During a 6-week regimen the girls lost 8.3±2.3 kg and reduced their body fat from 39.1±3.5 to 35.6±3.6%. In O1 but not in O2 WTR was reduced after weight loss (1.46±0.09 vs 1.51 ±0.10, p<0.01) indicating a preferential loss of abdominal fat. After weight loss E2, T, DHEAS were reduced and SHBG and T/E2 were increased in O1 (p<0.01) with only minor changes in O2. These data show that the sex steroid profile in obese adolescent girls is more dependent on the distribution of body fat than on its total amount. Girls with abdominal obesity, easily detectable by measuring WTR, have higher E2 and T levels but lower T/E2 than girls with gluteal-femoral obesity.