INTRODUCTION: Currently, no systematic review/meta-analysis has examined studies that used online social networks (OSN) as a primary intervention platform. Therefore, the purpose of this review was to evaluate the effectiveness of weight management interventions delivered through OSN. METHODS: PubMed, EMBASE, PsycINFO, Web of Science, and Scopus were searched (January 1990-November 2015) for studies with data on the effect of OSNs on weight loss. Only primary source articles that utilized OSN as the main platform for delivery of weight management/healthy lifestyle interventions, were published in English language peer-reviewed journals, and reported outcome data on weight were eligible for inclusion in this systematic review. Five articles were included in this review. RESULTS: One-hundred percent of the studies (n = 5) reported a reduction in baseline weight. Three of the five studies (60%) reported significant decreases in body weight when OSN was paired with health educator support. Only one study reported a clinical significant weight loss of >/=5%. CONCLUSION: Using OSN for weight management is in its early stages of development and, while these few studies show promise, more research is needed to acquire information about optimizing these interventions to increase their efficacy.