Early weight loss in a standalone mHealth intervention predicting treatment success

Objective: Early weight loss is a strong predictor of longer-term and clinically meaningful weight loss but has not been studied in the context of mobile health ('mHealth') interventions. Methods: GoalTracker was a randomized trial among adults (21-65 years) with overweight or obesity comparing three 12-week standalone mHealth interventions for weight loss. All arms received a free commercial mobile app (MyFitnessPal) for daily self-monitoring of diet and/or weight and a goal to lose 5% of weight by 3 months. Collapsing across arms, this analysis examined participants with a 1-month weight (n = 84), categorizing them as either early responders (≥2% weight loss at 1 month) or early non-responders (<2% weight loss at 1 month). Results: Early responders - 36% of participants - had greater per cent weight change at 3 months (-5.93% [95% confidence interval: -6.82%, -5.03%]) than early non-responders (-1.45% [-2.15%, -0.75%]), which was sustained at 6 months (-5.91% [-7.33%, -4.48%] vs. -1.28% [-2.37%, -0.19%]; ps < 0.0001). Over half (57%) of early responders achieved ≥5% weight loss at 3 months vs. 11% of early non-responders. At 4 weeks, self-monitoring frequency (weight/diet) was significantly greater among early responders, which continued across 12 weeks. Conclusion: Responding early to an mHealth treatment is associated with higher engagement and greater likelihood of achieving clinically meaningful weight loss.