Review of key findings from the OPTIWIN trial: Implications and future directions for medical weight management using total diet replacement

Over the past century, obesity and obesity-related comorbidities have become one of the greatest public health threats, and rates of morbidity and mortality continue to grow at alarming rates across the globe. Even modest amounts of weight loss from baseline can lead to significant improvements in quality of life, physical functioning, and remission of co-morbid conditions. Interventions to reduce excess weight vary from nutrition and surgical interventions, to pharmacotherapy, to lifestyle behavioral therapy. Findings related to the efficacy of various lifestyle behavioral interventions for the treatment of obesity continue to be mixed. The purpose of this article is to review key findings from the OPTIWIN obesity treatment trial, which tested the long-term effectiveness of a total meal replacement dietary intervention compared to a gold standard food-based lifestyle behavioral treatment for obesity. Overall, participants in the total meal replacement group lost significantly more excess weight and total fat mass, and demonstrated greater reductions in waist circumference during the active weight loss phase (baseline to 26 weeks), compared to the food-based group. These differences were maintained during the maintenance phase (26-52 weeks). The food-based group also had a higher proportion of non-responders (e.g., failure to lose ≥ 3% of their initial body weight) than the meal replacement group at 26 and 52 weeks. Implications for findings and future directions for medical weight management using lifestyle interventions and meal replacement methods are also discussed.