Polycystic ovary syndrome (PCOS) is the most common endocrinopathy, affecting up to 1 in 5 young women. PCOS is a multifaceted disorder with metabolic and reproductive implications. The condition places a significant burden of the healthcare system of ~$800 million per annum. Metabolic implications include obesity, insulin resistance, gestational diabetes, type 2 diabetes mellitus and risk factors for cardiovascular disease. Insulin resistance is a central characteristic in the majority of PCOS affected women, driving the clinical features including reproductive (hyperandrogenism, anovulation and infertility) and metabolic (increased type 2 diabetes risks) and cardiovascular risk factors. Not only have women with PCOS been shown to demonstrate insulin resistance that cannot be explained by BMI or visceral fat alone, but that obesity exacerbates all the clinical features and prevalence of PCOS. Underlying mechanisms of insulin resistance remain ill-defined, contributing to the controversy over diagnostic criteria, and a lack of optimal therapies Therapeutic strategies in PCOS include medical therapy (metformin), exercise and diet-induced weight loss, which all reduce, yet do not reverse insulin resistance and fail to optimally treat PCOS. . However, these approaches have provided insights into the aetiology of the condition. As such this presentation will contextualise current research in PCOS and explore the impact of obesity in this syndrome highlighting our current understanding of the molecular mechanisms of insulin resistance. Furthermore it will explore the impacts of lifestyle (diet and/or exercise) in preventing weight gain and how this evidence may inform further key research into the aetiology of PCOS and guide more effective therapies for this condition.