Differences in treatment response to a total diet replacement intervention vs. a food‐based intervention: a secondary analysis of the OPTIWIN trial

Objective For every weight loss treatment, there are usually groups of people who lose less than expected. This study sought to determine if response rates to a total diet replacement (TDR) differed from those of a calorie-restricted, food-based (FB) diet. Methods Data from OPTIWIN, a 12-month multicenter trial in adults with a BMI of 30-55 kg/m2, with 26-week weight-loss and weight-maintenance phases, were utilized. Participants (n = 330) were randomized to the OPTIFAST programme (OP) or to a reduced-energy FB diet. Treatment non-responders were defined as those who lost <3% of initial weight at months 6 or 12. Results There were 103 (76%) responders in the OP compared with 78 (57%) in the FB group at 12 months. The odds of treatment response at 12 months among participants who were non-responders at 3 months was not significantly different between the OP and FB groups (p = 0.64). Race, type 2 diabetes status and previous weight loss attempts were significantly associated with responder status. OP responders had higher meal plan adherence and non-caloric fluid intake compared with FB responders. Conclusion Early treatment response is more likely and better sustained with TDR compared with an FB diet. Individual and treatment level factors appear to influence early treatment response to behavioural interventions for weight reduction.