DESIGN: Population-based, retrospective cohort study. Participants were followed up for 5 years from 2006 to 2010. Mortality data were obtained via record linkages with the Malaysian National Registration Department. Multiple Cox regression was applied to compare risk of CVD and all-cause mortality between BMI categories adjusting for age, gender and ethnicity. Models were generated for all participants, all participants the first 2 years of follow-up, healthy participants, healthy never smokers, never smokers, current smokers and former smokers.

SETTING: All fourteen states in Malaysia.

SUBJECTS: Malaysian adults (n 32 839) aged 18 years or above from the third National Health and Morbidity Survey.

RESULTS: Total follow-up time was 153 814 person-years with 1035 deaths from all causes and 225 deaths from CVD. Underweight (BMI<18·5 kg/m2) was associated with a significantly increased risk of all-cause mortality, while obesity (BMI ≥30·0 kg/m2) was associated with a heightened risk of CVD mortality. Overweight (BMI=25·0-29·9 kg/m2) was inversely associated with risk of all-cause mortality. Underweight was significantly associated with all-cause mortality in all models except for current smokers. Overweight was inversely associated with all-cause mortality in all participants. Although a positive trend was observed between BMI and CVD mortality in all participants, a significant association was observed only for severe obesity (BMI≥35·0 kg/m2).