Could being overweight be good for the heart?

A new study has revealed that overweight patients may be at lower risk of cardiovascular mortality. This so called “obesity paradox” argues that being overweight might actually protect against certain medical conditions, in the case of these latest studies, against adverse cardiovascular outcomes.

The first study involved a meta-analysis of 36 studies that looked at the outcomes of patients with coronary artery disease (CAD) who underwent coronary revascularization procedures, including percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG).

Patients with a low body mass index (BMI) - less than 20 kg/m2 - had a 1.8- to 2.7-fold increased risk of heart attack and all-cause and cardiovascular mortality over the 1.7-year follow-up period.

Unexpectedly, patients with the lowest cardiovascular mortality risk were those who were overweight - a BMI of 25-30 kg/m2. In addition, patients who were obese (a BMI of 30-35 kg/m2) had a 27% lower risk of all-cause mortality than those with a normal BMI (20-25 kg/m2), while those who were severely obese (a BMI over 35 kg/m2) had a 22% lower risk of all-cause mortality.

Although the reasons for these findings are unclear, study leader Dr. Sharma, a cardiology fellow at the State University of New York Downstate Medical Center in Brooklyn, NY, explains that the findings could in part be explained by the fact that overweight patients are more likely to be prescribed medications that protect cardiovascular health

"Further," Sharma adds, “obese and overweight patients have been found to have large coronary vessel damage, which might contribute to more favourable outcomes. This population may have a higher metabolic reserve, which might act protectively in chronic conditions like CAD. Also, there could be a difference in the pathophysiology of cardiovascular disease in over- and underweight patients. A non-modifiable genetic predisposition may also play a role in underweight patients.”

Sharma concludes that this is still speculation. “Further prospective studies are needed to investigate this association and explore potential underlying mechanisms.”