Initial weight status moderates the impact of exercise referral schemes on improving patients’ Body Mass Index

Purpose To determine whether baseline body mass index (BMI) moderates BMI changes following completion of an exercise referral scheme (ERS). Design Retrospective analysis. Setting Data from the National ReferAll Database. Sample 634 adults out of 39,283 (64% female; mean age 54 ± 15 years). Intervention Participants completed a community-based ERS involving physical activity counseling and supervised exercise. Measures BMI was calculated as weight (kg) divided by height (m2) and participants were categorized by BMI: normal weight (<25.0 kg/m2), overweight (25.0-29.9 kg/m2), and obesity classes I (30.0-34.9 kg/m2), II (35.0-39.9 kg/m2), and III (≥40.0 kg/m2). Analysis A 5 × 2 mixed methods analysis of covariance, adjusted for age, sex, ERS type, and follow-up duration examined BMI changes over time by group. Linear regression assessed the relation between baseline BMI and BMI change. Results Baseline BMI predicted BMI reduction (β = −0.07 ± 0.01, 95% CI: −0.09 to −0.04, P < .001). Compared to the normal weight group, individuals with obesity classes I–III had significantly greater reductions in BMI (mean difference range: 0.83-1.01 kg/m2, all P < .001). No significant difference was observed between normal weight and overweight participants (P = .207). Conclusion This study provides evidence that ERS can be effective in improving BMI outcomes among individuals who have an elevated initial BMI. These findings support the continued development and refinement of ERS as a scalable public health strategy to promote weight-related improvements.