Patterns of Children's Weight Change During Family-Based Weight Management Intervention and Associations With Outcome Through Follow-Up.

INTRODUCTION: Understanding within-treatment weight change patterns may inform strategies to improve long-term outcomes for children with overweight/obesity. METHODS: Latent class modelling was applied to weekly weight change among 294 7-11-year-old children with overweight/obesity in behavioural weight management trials. Class differences in BMI z-score change through 1 year after treatment were examined using strict class assignment among completers (ANCOVA) or accounting for uncertainty in class assignment and missingness (Bolck, Croon and Hagenaars or BCH method). RESULTS: Three classes emerged-larger loss to stable weight (6% of children), consistent modest weight loss (43%) and moderate to decreasing weight loss (51%). During follow-up, the consistent modest weight loss class showed minimal change in BMI z-score whereas the other two classes increased (difference with moderate to decreasing weight loss class in ANCOVA = -0.096, p = 0.05; difference with large loss to stable class in BCH = -0.144, p = 0.017). The consistent modest weight loss class had the most favourable change from baseline through follow-up, better than the larger loss to stable weight class (ANCOVA difference = -0.189, p = 0.080; BCH difference = -0.186, p = 0.015). CONCLUSION: Three patterns of within-treatment child weight change emerged, with modest consistent weight loss associated with more favourable distal child outcomes.