Effectiveness of a digital intervention for weight loss maintenance in obese adults: the NULevel RCT

Abstract

Background: Scalable weight loss maintenance (WLM) interventions for obese adults are lacking but vital for the health and economic benefits of weight loss to be fully realised. We examined the effectiveness of a technology-mediated behavioural intervention to support WLM in obese adults after clinically-significant weight loss, compared to standard lifestyle advice. Methods: In open-label superiority RCT, we recruited 288 initially obese adults after recent weight loss of ≥5%. We randomly allocated participants 1:1 to either standard lifestyle advice via newsletter (control) or a technology-assisted behavioural WLM programme (intervention). The intervention included a single face-to-face meeting, self-monitoring and feedback on weight, diet and physical activity via links embedded in SMS messages. All participants received wirelessly-connected weighing scales and participants in the intervention arm were instructed to weigh themselves daily. After 12 months we measured change in weight from baseline, and also self-weighing, anthropometric variables, physical activity (accelerometry) and process variables. The study was powered to detect a between-group difference of ±2.5kg at 12 months. Findings: 253 participants (88%) were retained at 12 months. There were no intervention effects on weight at 12 months. Intervention participants weighed themselves more frequently than control participants (4 vs 2 times/week), showed higher levels of physical activity but did not differ on anthropometric characteristics or physical activity. Intervention participants reported greater satisfaction with weight outcomes, greater dietary self-efficacy and greater WLM confidence. Discussion: While the intervention was not effective in reducing weight regain, it increased physical activity, self-weighing and some, but not all other process measures.