Spline curve (solid line) and 95% CIs (dashed lines) representing the relationship between BMI and the HR for CVD (myocardial infarction, stroke, heart failure, or cardiovascular death). Estimates are adjusted for age, sex, education, physical activity levels, tobacco, and alcohol use. BMI 25 kg/m² is the reference. A histogram illustrating the distribution of BMI values in the study population is overlaid with frequency represented in the leftward vertical axis.