The prevalence of obesity and cardiovascular disease (CVD) has been increasing worldwide. Studies examining the association between adiposity and CVD outcomes have produced conflicting findings. The interplay between obesity and CVD outcomes in the general population and in specific subpopulations is complex and requires further elucidation.

We report updated evidence on the association between obesity and CVD events through a review of meta-analysis studies. This review identified that obesity or high body mass index (BMI) was associated with an increased risk of CVD events, including mortality, in the general population and that cardiac respiratory fitness (CRF) and metabolic health status appear to stratify the risk of CVD outcomes. In patients with diabetes, hypertension, or coronary artery disease, mortality displayed a U-shaped association with BMI. This U-shaped association may result from the effect of unintentional weight loss or medication use. By contrast, patients with other severe heart diseases or undergoing cardiac surgery displayed a reverse J-shaped association suggesting the highest mortality associated with low BMI. In these conditions, a prolonged intensive medication use might have attenuated the risk of mortality associated with high BMI.

For the general population, a large body of evidence points to the importance of obesity prevention and maintenance of a healthy weight. However, for those with diagnosed cardiovascular diseases or diabetes, the relationship between BMI and cardiovascular outcomes is more complex and varies with the type of disease. More studies are needed to define how heterogeneity in the longitudinal changes in BMI affects mortality, especially in patients with severe heart diseases or going under cardiac surgery, in order to target subgroups for tailored interventions. Interventions for managing body weight, in conjunction with improving CRF and metabolic health status and avoiding unintentional weight loss, should be used to improve CVD outcomes.