Drawing illustrating the interaction between weight and insulin resistance, leading to augmentation of luteinising hormone (LH)-stimulated androgen (A) secretion, resulting in development of polycystic ovary syndrome (PCOS). Drawing illustrating the interaction between weight and insulin resistance, leading to augmentation of luteinising hormone (LH)-stimulated androgen (A) secretion, resulting in development of polycystic ovary syndrome (PCOS). See text for an explanation of stages a–d. W Colin Duncan J Fam Plann Reprod Health Care 2014;40:217-225 Copyright © by the BMJ Publishing Group Ltd & the Faculty of Sexual & Reproductive Healthcare of the Royal College of Obstetricians & Gynaecologists. All rights reserved.