Background: Obesity remains an underestimated contributor to global cancer incidence and cancer-related mortality. Accumulating evidence suggests excessive energy intake and suboptimal levels of physical activity may be important after the diagnosis of cancer and may influence recurrence and overall survival(OS). Objective: Conduct a systematic review to evaluate data from randomized trials of weight control strategies used in breast cancer patients. Methods: A systematic search of Medline, Embase and the Cochrane Register of Controlled Trials through April 2015 was performed. Randomized trials of weight management strategies in breast cancer patients were sought. Outcomes studied included; change in weight, BMI and waist circumference, disease-free survival, recurrence-free survival and OS survival. Random effects meta-analyses were planned provided that included studies were considered to be clinically and methodologically homogenous. Results: Of 2876 abstracts, 312 were retained for review of the full texts. Overall 43 publications describing 40 studies met inclusion criteria. Of 12,801 enrolled patients, 11,597 had breast cancer. Fifteen studies consisted of dietary interventions, 17 consisted of exercise interventions and 8 consisted of both dietary and exercise interventions. Endpoints included: changes in weight (32 studies, 7,861 pts), BMI (12 studies, 1,886 pts), waist circumference (10 studies, 702 pts), recurrence-free survival (4 studies, 6105 pts) and overall survival (2 studies, 3,330 pts). Network meta-analyses of available data are in progress. Study results suggest that weight control strategies including dietary and exercise interventions were effective at reducing weight, BMI and waist circumference. Two large studies showed statistically significant recurrence-free survival benefits with weight control strategies and one showed OS benefit with an exercise intervention. Conclusions: Data from included trials suggest benefits of weight control strategies to decrease weight, BMI and waist circumference. Few trials have been designed to detect PFS or OS benefits. Larger trials are warranted to better define the role of weight control strategies in the management of breast cancer patients.