Association of healthy lifestyle with coronary artery disease risk varies by weight status: a prospective cohort study

Background A healthy lifestyle reduces the risk of coronary artery disease (CAD). However, whether this observed association varies by weight status remains unclear. This study aimed to evaluate the relationship between a healthy lifestyle and the risk of CAD across different weight statuses. Methods This prospective cohort study included 8,787 Chinese adults recruited from a health examination center. We developed a healthy lifestyle score (0–4 points) based on smoking, drinking, physical activity, and diet. Participants were classified as normal weight (18.5 ≤ BMI < 24.0) or obesity (BMI ≥ 28 kg/m 2 ). The primary outcome was the incidence of CAD. Cox proportional hazards regression models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI), stratified by weight status, and interaction effects were assessed. Results Over a median follow-up period of 7 years, 476 CAD events occurred. Each 1-point increase in lifestyle score was associated with a 24% reduction in CAD risk (HR = 0.76, 95% CI: 0.68–0.86). Stratified analysis revealed a significant inverse association in normal-weight individuals (HR = 0.75, 95% CI: 0.65–0.86), while the association in the obesity group did not achieve statistical significance (HR = 0.85, 95% CI: 0.67–1.07). The interaction between lifestyle score and weight status was not statistically significant ( p for interaction = 0.464). Joint effect analysis indicated that obese individuals with an unhealthy lifestyle exhibited the highest CAD risk (HR = 1.58, 95% CI: 1.13–2.21). Conclusion A healthy lifestyle is significantly associated with a reduced risk of CAD among normal-weight individuals. In contrast, this association is not statistically significant in obese individuals, suggesting potential heterogeneity in the relationship between healthy lifestyle scores and CAD risk based on weight status. Given the observational design and limited power in some subgroup analyses, the results should be interpreted as hypothesis-generating and require confirmation in larger prospective studies.