Polycystic ovary syndrome (PCOS) affects up to 18 of reproductiveaged women (March et al., 2010) and is associated with reproductive (hyperandrogenism, menstrual irregularity, anovulation, infertility, pregnancy complications), metabolic (elevated risk factors for type 2 diabetes mellitus and cardiovascular disease and elevated prevalence of type 2 diabetes mellitus and cardiovascular disease) and psychological characteristics (worsened quality of life and elevated prevalence of anxiety and depression; Teede et al., 2011). Insulin resistance is a pathophysiological feature of PCOS and is proposed to be mechanistically distinct (or intrinsic) from obesity-associated insulin resistance. Insulin resistance present in the majority of women with PCOS, including lean women (Dunaif et al., 1989), and worsens the clinical presentation. Weight gain further compounds insulin resistance (Erdmann et al., 2008). Given the association between insulin resistance, obesity and the presentation of PCOS, weight management is a key initial treatment strategy for PCOS(Teede et al., 2011) and improves the reproductive, metabolic and psychological features (Moran et al., 2011). There is emerging evidence that women with PCOS have an elevated risk of being overweight and obese and have increased longitudinal weight gain compared with community controls (Teede et al., 2013). Arecent meta-analysis has reported increased prevalence of overweight or obesity [1.95 risk ratio; 95 confidence interval (CI) 1.52?2.50] for women with PCOS compared with controls (Lim et al., 2012). We have proposed that there is a bidirectional interaction between PCOS and weight with PCOS driving weight gain and weight gain contributing to an increased prevalence and severity of PCOS (Teede et al., 2013). Indeed, women with PCOS may have specific physiological or intrinsic barriers to maintaining a healthy weight such as insulin resistance, hyperinsulinaemia and hyperandrogenism, which can contribute to weight or abdominal fat gain (1988, Pasquali, 2006), reduce energy expenditure and increase food intake (Felig, 1984; Welle et al., 1988; Franssila- Kallunki and Groop, 1992; Robinson et al., 1992; Carlson and Campbell, 1993; Kersten, 2001; Moran et al., 2004; Hirschberg et al., 2004; Georgopoulos et al., 2008; Ryan et al., 2008).Women with PCOS may additionally have altered energy balance caused by extrinsic factors, supported by reports of reduced physical activity (Eleftheriadou et al., 2012) and increased intake of high glycaemic index foods compared with controls (Douglas et al., 2006). Conversely, other research suggest no differences in energy or dietary intake such as macronutrient, micronutrient or food group intake, physical activity or muscle strength between lean or overweight women with or without PCOS (Wright et al., 2004; Douglas et al., 2006; Thomson et al., 2009). Given the prevalence and health burden ofPCOSand the propensity to, and adverse impact of excess weight in PCOS, it is important to explore potentiallymodifiable extrinsic or environmental factors that may contribute to obesity inwomenwith PCOSto guidemanagement. The aim of this studywas to examine the association of demographic variables and extrinsic factors, includingdiet andphysical activity, withbodymass index (BMI) in a large community study of women with and without diagnosed PCOS.