Background Weight loss through behavioural weight management interventions can have important health benefits for people with obesity and can be cost-effective if weight loss is maintained long-term. However, concerns have been raised that such interventions may exacerbate health inequalities by being less effective in more disadvantaged groups. In a recent systematic review, we found no evidence that disadvantaged groups had worse weight outcomes during behavioural weight loss interventions. However, no study has considered whether inequalities exist in weight regain after the intervention ends. We aimed to investigate if there are inequalities in weight change following participation in a weight loss intervention.

Methods We conducted a cohort analysis of data from the Weight Loss Referrals for Adults in Primary Care [WRAP] trial (N=1267). WRAP randomised participants to receive a brief intervention information booklet or vouchers for 12-weeks or 52-weeks of WW (formerly Weight Watchers) and followed them for 5 years. Multiple linear regression models were used to estimate the association between exposures (indicators of inequality) and outcome (change in weight between 1-year and 5-years). Each model was adjusted for intervention group, baseline weight, weight change between baseline and 1-year, research centre, and source of the 5-year weight data (study measured, extracted from GP records or self-reported). A complete case analysis was performed.

Results Of the 1267 participants in WRAP, 708 had weight data available at the 1- and 5-year time points. Mean weight change between 1- and 5-years was +3.30 kg (SD 9.10 kg). Baseline age was associated with weight change between 1- and 5-years; a 1 year difference in age at baseline was associated with a change of 0.11kg ((95%CI 0.06, 0.16), p<0.001). We did not find evidence of associations between ethnicity, sex, education, indices of multiple deprivation, household income, or other family members participating in a weight loss programme and weight change between 1- and 5-years.

Conclusion Except for age, we did not find evidence of inequalities in weight regain following a behavioural intervention. Younger participants may need additional support following participation in a behavioural weight management programme to maintain attained weight loss. Findings further support the use of behavioural weight management interventions as part of a systems wide approach to improving population health.