The Relation of Grit to Weight Loss Maintenance Outcomes.

Biological, genetic, and environmental factors make weight loss very difficult. Acceptance-based behavioral treatment (ABT) supplements standard behavioral treatments (BT) for obesity by teaching skills to accept the discomfort inherent to weight control behaviors and prioritize long-term, values-based goals. Grit, the ability to persevere in goal pursuit, overlaps conceptually with ABT principles and may predict outcomes in ABT. During a randomized controlled trial comparing three weight loss interventions (BT, BT with an emphasis on physical activity [BT+PA], ABT with an emphasis on physical activity [ABT+PA]), this study examined if grit predicted weight loss, intervention engagement (session attendance and dietary self-monitoring), and perceived intervention effectiveness, and whether intervention condition moderated these relationships. Participants (N=309) with overweight/obesity enrolled in an 18-month weight loss intervention completed the Short Grit Scale at baseline. Weight and PA were measured at baseline, during the intervention (12 and 18 months), and at follow-up (24 and 36 months). Session attendance and dietary self-monitoring were assessed throughout the intervention, and perceived intervention effectiveness at end-of-intervention. The relation of grit to several outcomes depended on condition. In ABT+PA, but not BT or BT+PA, lower grit related to higher weight loss at 12 and 24 months, session attendance, and perceived intervention effectiveness. Grit was not related to PA or dietary self-monitoring in any condition. ABT's focus on building skills to facilitate long-term goal pursuit may be unique and beneficial to those with lower grit. Those with higher grit may already possess ABT-consistent skills and benefit less from ABT. Research on trait-level characteristics like grit in relation to weight must be cautious not to reinforce weight bias; rather, this work suggests that an evidence-based intervention (ABT) may be well-suited to those with lower grit levels seeking weight loss.