Weight loss maintenance is one of the most critical challenges for obesity treatment. Recruiting people to a maintenance intervention after they have
lost weight can provide maintenance-tailored intervention messages and support when they are at highest risk for weight regain has potential to enhance long-term weight control. The Keep It Off trial is a randomized controlled trial of an interactive phone-based intervention to help adults who have recently intentionally lost at least 10% of their body weight, maintain that weight loss over a 24-month period. 419 eligible adult men and women were randomized to either the Self-Directed Intervention, Comparison Condition, or the Guided Intervention. Primary study outcomes are 24-month weight change and percent achieving weight loss maintenance. Secondary aims include: a) subgroup analysis of intervention effectiveness (e.g., BMI status, weight loss method); b) mediating factors (e.g., self-efficacy, physical activity, dietary intake, social support); c) process measures (e.g., adherence) as predictors of weight outcomes; and d) intervention costs to evaluate intervention scalability. About 82% of participants are female; average age is 47 years; and average baseline BMI was 28 kg/m2. The average amount of weight lost prior to study entry was 16% of starting body weight. About one third of participants reported losing weight with the assistance of a formal weight loss program, with the remainder reporting a self-initiated diet and/or exercise plan. The Keep It Off study offers a potentially efficacious approach to the perennial problem of weight regain. By recruiting participants after they have already lost weight to an intervention focused explicitly on maintenance, the intervention holds promise for modifying the typical relapse curve. If shown to be efficacious, the use of phone-based intervention delivery offers potential for widespread dissemination.