Effects of low-dose estrogen oral contraceptives on weight, body composition, and fat distribution in young women.

OBJECTIVE: To determine prospectively whether the use of low-dose estrogen oral contraceptives (OC) is associated with changes in weight, body composition, or fat distribution. DESIGN: Anthropometric measurements were performed in 49 healthy young (16 to 21 years old) women before commencement of OC use (30 micrograms ethinyl estradiol [EF2] plus 75 micrograms gestodene) and after three and six treatment cycles. Thirty one age- and weight-matched women who were not using OC served as controls. SETTING: Outpatient gynecological clinic of Hadassah Medical Center, a tertiary level hospital, and the "Shilo" voluntary service for the prevention of unwanted pregnancy. MAIN OUTCOME MEASURES: Anthropometric measurements included body mass index (BMI), waist-to-hip girth ratio, and body composition (the percentage of body fat and water), estimated by mean of infrared interactance. RESULTS: In the group of OC users, baseline BMI, percent fat, percent water, and waist-to-hip girth ratio were 21.1 +/- 0.32 (kg/m2), 23.8% +/- 0.63%, 57.4% +/- 0.39%, and 0.73 +/- 0.01, respectively, and did not change significantly after six cycles (20.6 +/- 0.41 [kg/m2], 23.9% +/- 0.57%, 58.1% +/- 0.49%, and 0.72 +/- 0.03, respectively). These measurements were not significantly different when compared with the nonusers. Fifteen OC users (30.6%) gained weight (> 0.5 kg). Weight gain was due to a significant accumulation of fat (from 22.5% +/- 1.1% to 25.6% +/- 0.74%), whereas the percentage of body water remained stable. The waist-to-hip girth ratio also was not changed significantly. Similarly, 11 nonusers (35.4%) gained weight because of similar nonabdominal fat accumulation. Ten OC users (20.4%) lost weight (57 kg +/- 1.51 to 55.4 +/- 1.47 [mean +/- SEM]) and 6 nonusers (19.3%) also lost weight (59 kg +/- 1.42 to 57.3 +/- 1.92). In both groups the loss of weight was not associated with significant change in body composition. CONCLUSIONS: The use of low-dose OC (EE2 plus gestodene) was not associated with overall impact on weight, body composition, or fat distribution. However, when weight gain did occur during OC use, it was due to increase in body fat and not in volume of body water, and it was not associated with changes in fat distribution.