Background: It is not clear why some anovulatory women with polycystic ovary syndrome (PCOS) and obesity resume ovulation and others remain anovulatory after weight loss. The objective of this study was to compare the changes in body fat distribution and specifically intra-abdominal fat (IAF) and subcutaneous abdominal fat (SAF) between a group of anovulatory women with PCOS and obesity who resume ovulation (RO+) to those who remain anovulatory (RO-) during a lifestyle program.
Methods: In a prospective pilot cohort study, anovulatory women with PCOS underwent a 6 month lifestyle program in a tertiary fertility clinic. Body fat distribution was assessed by anthropometrics, dual-energy X-ray absorptiometry (DEXA) and single slice abdominal CT scan at intake, after 3 months and after 6 months. Baseline-corrected changes over time were analysed using generalized estimating equations longitudinal regression analysis.
Results: In 32 anovulatory women with PCOS (age, 28 ± 4 years; BMI, 37.5 ± 5.0 kg/m²), there were no significant baseline differences in anthropometrics and biochemical assessment between 14 RO+ participants and 18 RO- participants. RO+ women lost more weight (6.3 versus 3.0%) and abdominal fat on DEXA (15.0 versus 4.3%) compared with RO- women. Resumption of ovulation was associated with early and consistent loss of IAF (12.4 versus 5.0% at 3 months and 18.5 versus 8.6% at 6 months). Loss of SAF between the RO+ women and the RO- women was similar at 3 months (6.2 versus 6.1%) but did not change any further in RO- women (6.1%) as it did in RO+ women (11.4%) at 6 months.
Conclusions: In anovulatory women with PCOS and obesity undergoing a lifestyle program, RO+ women lose more body weight and abdominal fat on DEXA than RO- women. In addition, this study shows that early and consistent loss of IAF is associated with resumption of ovulation. Future studies should address the mechanisms behind these changes and should assess interventions aimed at loss of IAF to facilitate resumption of ovulation.