Current prospects of metabolically healthy obesity

Abstract

Obesity is a heterogeneous disorder posing a great risk of developing cardiovascular disease and type 2 diabetes. Metabolically healthy obesity (MHO) is a phenotype claimed to be protected against these risks, but its mechanisms remain unclear. Overview of current evidence indicating MHO and its metabolic characteristics, highlighting possible factors underlying MHO. PubMed, Medline, Clinical trials.gov, Science Direct, ADI, and WHO databases were searched through to June 2021 . Recent evidence shows MHO phenotype with a prevalence of 6–75% and claims protection from cardiometabolic complications, though its precise definition and diagnosis are not yet established. Although MHO individuals are not healthy and may represent a subclinical state of obesity, they are closer to normal than those with other obesity phenotypes concerning adipocyte size and distribution, immune cell infiltration, adipokine secretion, cardiorespiratory fitness, proinflammatory biomarkers, insulin sensitivity, and dietary response. Notably, 36–52% of MHO individuals may become unhealthy later in life, though the evidence is inconclusive. MHO phenotype remains a controversial scientific issue, especially for its definition. MHO individuals are classified to have fewer or milder metabolic risks than those with unhealthy phenotypes; some maintain a healthy lifestyle and fat and fit. Thus, in-depth research is warranted. • Metabolic healthy obesity (MHO) shows reduced cardiometabolic risks. • There is no precise definition and diagnosis of MHO yet. • Although not healthy, MHO individuals are closer to normal than other phenotypes. • Evidence that MHO individuals may become unhealthy later in life is inconclusive. • The MHO phenotype remains a controversial scientific issue.