People with ID have an increased risk for unhealthy diets, physical inactivity and weight disturbances. The aim of the current study was to investigate the effectiveness of a novel and complex intervention to improve diet and physical activity, targeting both caregivers and residents, in community residences for people with ID. A three component intervention based on Social Cognitive Theory was developed, including: (1) appointment of a health ambassador in each community residence attending network meetings, (2) a study circle for caregivers, and (3) a health course for the residents. The intervention lasted for 12–16 months and allowed for some local tailoring. A cluster randomised controlled trial, randomised at residence level, was conducted to evaluate the effects of the intervention. Thirty community residences for people with mild or moderate ID in Stockholm County, Sweden, were included. A total of 130 participants, 74 women and 56 men aged 20–66 years, entered, and 129 participants completed the study. The primary outcome was physical activity, measured by pedometry. Secondary outcomes were BMI, waist circumference, dietary quality measured by digital photography, satisfaction with life assessed with a scale, and work routines assessed with a questionnaire. Outcomes were related to intervention fidelity. A positive intervention effect was found on physical activity, with an average increase of 1608 steps/day among participants in the intervention group (P = 0.045). The effect size was 0.29 (Cohen's d). The type of residence was found to be an effect moderator. A positive intervention effect was found as well on work routines, with an average increase of 7.1 percentage points on a self-assessment scale among residences in the intervention group (P = 0.016). No significant effects were found on BMI, waist circumference, dietary quality, or satisfaction with life. In conclusion, this innovative intervention was effective in improving physical activity and work routines. It is likely that even greater effects could be achieved by improvements in implementation strategies, leading to higher fidelity.
