Body fat and cardiovascular risk: understanding the obesity paradox

Large studies of initially healthy men and women consistently link adiposity with an increased risk of cardiovascular events.1,2 Compared with a reference body mass index (BMI) <25 kg/m2, the relative risk of dying during the next decade ranges from 1.2 for overweight (25–29.9 kg/m2) to 3.8 for severely obese (≥40 kg/m2) subjects, after adjustment for age, smoking, alcohol, and physical activity.1 Abdominal fat, measured as the waist–hip ratio, more reliably predicts the risk of ischaemic heart disease and death than BMI, even within normal body weights and after additional adjustment for blood pressure and cholesterol.2,3 In striking contrast, among patients with known atherothrombotic diseases4,5 or multiple risk factors,6 just the opposite is seen (‘obesity paradox’): the leanest fare worse4 and the heavier fare better than the normal weight reference groups.4–6 Among stable hypertensive ischaemic heart disease patients, thin (<20 kg/m2) compared with normal weight patients had a 3-year hazard of death, non-fatal myocardial infarction, and non-fatal stroke of 1.5, similar to that conferred by a 10-year increment in age.4 At the other extreme, obese and very obese patients with non-ST-elevation acute coronary syndromes had a 3-year hazard of dying of 0.3 compared with normal BMI patients.5 … *Corresponding author. Tel. +39 06 30154187, Fax +39 06 3055535, Email: felicita.andreotti{at}iol.it