Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women. Many of these women are overweight or obese. A minor weight loss of 5%-10% can significantly reduce reproductive, metabolic and psychological symptoms of PCOS and is recommended as a first step in the treatment of overweight or obese women with PCOS. Many weight loss programs have been proposed, but optimal methods on how to achieve the recommend weight loss are lacking. The aim of this systematic review was to generate practical tools for health professionals to guide women with PCOS towards a sustainable healthier lifestyle. PRISMA guidelines were used to conduct the systematic review. Eleven randomized controlled trials were found eligible for inclusion. Lifestyle modification strategies consisted of a diet, physical exercise, behavioural coaching or combined interventions. Mean weight loss ranged from +0.5 to -10.6 % of the initial body weight. However, the majority of the studies reported considerable drop-out rates varying between 12% and 47%. The heterogeneity of the described interventions and the high drop-out rates impede extrapolation of these results to daily clinical care. Hence, none of the described interventions seems superior to another in achieving substantial weight loss. In conclusion, the need for obtaining a healthier weight in overweight and obese women with PCOS is now well accepted. However, achieving this goal remains a challenge for both patients and healthcare providers. More research focusing on the multidisciplinary approach of lifestyle modification advice in daily practice is needed.