Metabolic and cardiovascular implications of a metabolically healthy obesity phenotype

Abstract

Metabolically healthy obesity (MHO) is a new concept in which an individual may exhibit an obese phenotype in the absence of any metabolic abnormalities. There are a number of definitions of MHO that utilize a variety of components. The findings of clinical and basic studies indicate that subjects with MHO do not exhibit an increased mortality, an increased risk of cardiovascular disease, or an increased risk of type 2 diabetes mellitus, as compared to normal-weight controls. Although these findings imply that metabolic health is a more important factor than obesity, several studies have shown that subjects with MHO have a similar risk of metabolic or cardiovascular diseases as those with metabolically unhealthy obesity. Thus, there is still debate regarding not only the implications of the MHO phenotype but its very existence. Accordingly, future studies should focus on developing a unified definition of MHO and distinguishing subjects who will be at a high risk for metabolic and cardiovascular diseases.

Keywords: Cardiovascular diseases; Diabetes; Metabolically healthy obesity.

Fig. 1

Possible pathophysiologies of metabolically healthy obesity and metabolically unhealthy obesity. The gene-environment interactions may play dual roles as both causative factors for the development of obesity and for the dissociation of obesity into subphenotypes of physiological (predominantly subcutaneous, insulin sensitive, and healthy) or pathological (visceral, ectopic, and unhealthy) fat accumulation. Adapted from Bluher, Curr Opin Lipidol 2010;21:38-43, with permission from Wolters Kluwer Health [10].

Fig. 2

Proposed features of preserved metabolic health in obese humans. Adapted from Samocha-Bonet et al. Obes Rev 2014;15:697-708, with permission from John Wiley and Sons [20].