Abstract
BACKGROUND: There is limited evidence and clinical guidelines on the behavior change support required for low-calorie diet programs. This systematic review aimed to establish the behavior change technique(s) (BCT) implemented in weight loss interventions (≤1200 kcal/d) and how these contribute to effectiveness. METHODS: Databases were searched from inception to April 2022. Screening, data extraction, BCT coding, and quality appraisal were conducted in duplicate using the Template for Intervention Description and Replication framework, Behavior Change Technique Taxonomy, and Cochrane Risk of Bias 2 tool. Data were analyzed via narrative synthesis and random effects multi-level meta-analyses. RESULTS: Thirty-two papers reporting on 27 studies were included. Twenty-four BCTs were identified across studies. Eight BCTs were significantly associated with a larger reduction in weight at the end-of-diet time-point; one BCT was statistically significant at the end of weight maintenance. Physical activity, Type 2 Diabetes, and BMI category moderated intervention effects. CONCLUSIONS AND IMPLICATIONS: This is the first meta-analysis to examine how specific BCTs contribute to the effectiveness of low-calorie diets. It is recommended that a) these findings are used to develop clinical guidelines specific to behavioral support in low-calorie diet programs, and b) program commissioners stipulate the use of these BCTs in their service specifications.