Carrying a heavier weight is healthy: Obesity‐reinforced fitness hypothesis in metabolically healthy obesity

Over 50 years ago, the Framingham Heart Study linked obesity with coronary heart disease and cardiovascular death. Two decades later, the term “metabolic syndrome” was coined to explain the association of obesity, diabetes mellitus, and a few other risk factors with atherosclerosis. The link between obesity and cardiovascular disease is believed to be through a number of metabolic pathways and their complications such as atherogenic dyslipidemia, elevated blood pressure, and elevated plasma glucose. However, recent data suggest that in some people obesity may be devoid of metabolic complications and without increased risk for cardiovascular morbidity and mortality, the so-called “metabolically healthy obesity” (MHO). Indeed higher body mass index (BMI) values in the overweight to mild obesity range (25-35 kg/m) may confer certain survival advantages in both the general population (1) and some chronic disease states such as chronic kidney disease (2) and heart failure (3) as well as among the elderly (4). Nevertheless, MHO may still be linked to a higher risk of type 2 diabetes mellitus (5). In addition, heavy weight is associated with other non-cardiovascular sequelae such as osteoarthritis, chronic back pain, gallbladder disease, asthma, and various cancers. Nonetheless, evidence is overwhelming that there may be biologic plausibility beyond statistical findings related to MHO.