Weight regain after initial loss is extremely common and a major barrier to healthy weight control. Following weight loss, participants are encouraged to self-weigh daily and immediately take action to reverse small weight regains before they can escalate. However, research continually shows that, when participants notice a small weight regain, they rarely attempt to actively address it; instead, they tend to avoid the behaviors necessary to reverse the gain. To prevent goal disengagement, interventions must help participants cope with the distress and demoralization of weight regain. Psychological strategies of mindfulness, acceptance, and self-compassion (MASC) are commonly used in therapeutic frameworks designed to help people cope with distress (e.g., Acceptance and Commitment Therapy), and may be an especially good fit for promoting adaptive responses to weight regain. To maximize their effectiveness, these strategies must be administered immediately after the participant experiences weight regain, before the cycle of weight regain and disengagement becomes entrenched. Just-in-time adaptive interventions (JITAIs) can deploy these interventions in the moments after a weigh-in, as soon as the participant starts to disengage.

The proposed study tests the feasibility, acceptability, and effectiveness of JITAIs that use MASC strategies to promote adaptive responses to weight regain. Adults (N=120) with overweight/obesity who have recently lost a significant amount of weight and want to maintain or lose more will be randomized to a condition that receives JITAIs through a mobile app whenever they experience weight regain or skip a weigh-in, or to an active control condition.