Does being overweight really reduce mortality?

Abstract

There is indisputable evidence from epidemiologic and clinical studies that being overweight and obese elevates the risk of developing debilitating and costly chronic diseases, including hypertension, hypercholesterolemia, type 2 diabetes, cardiovascular diseases (CVD), and cancer (1). Nonetheless, the relationship between body mass index (BMI) and mortality remains the subject of much debate. A recent meta-analysis concluded that compared to those of normal weight (BMI<25.0), overweight individuals (BMI 25.0–29.9) had a significantly lower mortality risk (2). Even Class 1 obesity (BMI 30–34.9) was associated with marginally reduced mortality. In this Perspective, we discuss why this finding is likely to be an artifact of methodological limitations and what the clinical and public health implications may be.