Weight gain is a common among women treated for breast cancer, particularly among women who are pre-menopausal at diagnosis and those undergoing chemotherapy. Obesity and weight gain have been associated with poor disease-specific and health-related outcomes. This review aimed to evaluate the effectiveness of weight gain prevention interventions for women diagnosed with breast cancer. Studies were identified through a systematic search of Pubmed, Embase, CINAHL and Scopus from inception to April 2016. A search of clinical trials registers was also conducted. Completed and ongoing trials evaluating a behaviourally based dietary intervention with or without physical activity and with a focus on weight gain prevention in women with breast cancer were reviewed. Weight change and body composition data were extracted. Within-group weight change of ±1kg and between-group weight differences of ≥2kg was defined as successful weight gain prevention. Five completed trials and six ongoing trials were identified. All completed trials were conducted in women undergoing chemotherapy treatment and recruited exclusively premenopausal or both pre- and postmenopausal women. Studies were primarily underpowered pilot trials, and all considered to have a moderate or high risk of bias. Within-group weight gain prevention was achieved in two studies, with intervention groups in two studies losing >1kg. Between-group (intervention vs control) weight change of ≥2kg was achieved by two studies. No trials assessed outcomes following the end-of-intervention or cost-effectiveness. Ongoing trials will further contribute to the evidence base by addressing some of the limitations in the existing evidence. This small but growing number of studies reviewed provides preliminary and promising evidence that weight gain can be prevented in women with breast cancer undergoing chemotherapy treatment. Future studies should assess outcomes following the end-of-intervention, promote resistance training, assess bone density and assess cost-effectiveness.