Effectiveness of a Total Meal Replacement Program (OPTIFAST Program) on Weight Loss: Results from the OPTIWIN Study

Abstract

Objective: The aim of this study was to test the effectiveness of the OPTIFAST program (OP), a total meal replacement dietary intervention, compared with a food-based (FB) dietary plan for weight loss. Methods: Participants with BMI 30 to 55 kg/m2, age 18 to 70 years old, were randomized to OP or FB dietary and lifestyle interventions for 26 weeks, followed by a weight-maintenance phase. Outcomes were percent change in body weight (%WL) from baseline to weeks 26 and 52, associated changes in body composition (using dual energy x-ray absorptiometry), and adverse events. Primary analysis used repeated-measures multivariable linear mixed models to compare outcomes between groups in a modified intention-to-treat fashion (mITT). Results: A total of 273 participants (83% of randomized; 135 OP, 138 FB) made up the mITT population. Mean age was 47.1 ± 11.2 years; 82% were female and 71% non-Hispanic white. Baseline BMI was 38.8 ± 5.9 kg/m2. At 26 weeks, OP %WL was 12.4%±0.6% versus 6.0%±0.6% in FB (P <0.001). At 52 weeks, OP %WL was 10.5% ± 0.6% versus 5.5% ± 0.6% in FB (P < 0.001). Fat mass loss was greater for OP; lean mass loss was proportional to total weight loss. There was no difference in serious adverse event rates between groups. Conclusions: Compared with an FB approach, OP was more effective with greater sustained weight loss.