Process evaluation of a cluster-randomised controlled trial of multi-component weight management programme in adults with intellectual disabilities and obesity.

BACKGROUND: Providing effective weight management to adults with intellectual disabilities is necessary to challenge the high rates of obesity. The aim of this process evaluation was to explore the feasibility of conducting a full-scale clinical trial of the TAKE 5 multi-component weight management programme. METHODS: The study was a 12-month pilot cluster-randomised controlled trial. Adults with intellectual disabilities and obesity were randomised to either TAKE 5, which included an energy deficit diet (EDD) or Waist Winners Too, based on health education principles. A mixed-methods process evaluation was conducted focussing on the reach, recruitment, fidelity, implementation, dose (delivered/received) and context. RESULTS: The study successfully recruited adults with intellectual disabilities. Both weight management programmes were delivered with high fidelity and implemented as intended. Only one weight management programme, TAKE 5, demonstrated potential efficacy in reducing body weight and body composition. The effectiveness was largely attributed to the EDD and social support from carers. CONCLUSIONS: The extensive process evaluation illustrated that a full-scale trial of a multi-component programme including an EDD is feasible and an acceptable approach to weight management for adults with intellectual disabilities and obesity.