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 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 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 2941 abstracts, 312 were retained for review of the full texts. Sixty-four publications describing 47 studies met the inclusion criteria, including 10,411 enrolled patients. Overall, 13 studies consisted of dietary interventions, 21 consisted of exercise interventions and 13 consisted of both dietary and exercise interventions. Endpoints included changes in weight (39 studies, 9,947 pts), BMI (30 studies, 5,784 pts), waist circumference (20 studies, 1,546 pts), recurrence-free survival (3 studies, 5,767 pts) and overall survival (3 studies, 5,767 pts). Network meta-analyses of available data are in progress. Study results suggest that weight control strategies including dietary and exercise interventions may be 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 cancer patients and cancer survivors.