Obesity and cardiovascular disease: friend or foe?

Obesity is currently one of the greatest public health issues worldwide. However, despite its known deleterious effects on the cardiovascular system and its association with numerous cardiovascular diseases (CVD), recent findings leading to the development of concepts such as metabolically healthy obesity, the obesity paradox, and protective subcutaneous fat depots have raised a lively debate on the disparate effects of obesity on health outcomes. Regarding the concept of metabolically healthy obesity, by presumably labelling a subset of obese people as metabolically healthy, physicians may not feel pressed to curb the current obesity epidemic and prevent the next generation of people from becoming obese. Another issue is that the most commonly used anthropometric index to define obesity, the body mass index, is at the core of the controversy because of its limitations including its inability to discriminate between fat mass and muscle mass. Many recent epidemiological and metabolic studies have used other indices such as waist-hip ratio, waist circumference, and imaging (computed tomography or magnetic resonance imaging) measurements of visceral adiposity and of ectopic fat depots. In addition, emerging evidence supports the importance of cardiorespiratory fitness, skeletal muscle mass and strength in patients with obesity as useful variables to predict CVD risk beyond adiposity. In this review, we will discuss the complex and disparate effects of obesity on CVD, particularly focusing on whether, under given circumstances, it could be harmful, potentially harmless or neutral, or even possibly protective.