Invited commentary: limitations and usefulness of the metabolically healthy obesity phenotype.

The fraction of the obese population who appear to be free of the metabolic abnormalities that usually accompany excess adiposity has garnered a great deal of attention recently. The so-called "metabolically healthy obesity" concept is thought to offer a refinement of the traditional obesity definitions that are based solely on anthropometry. The commentary by Rey-López et al. (Am J Epidemiol. 2015;182(9):737-741) in this issue of the Journal highlights several limitations of the "metabolically healthy obesity" concept and calls into question its usefulness as a public health metric. We discuss several of the issues raised by these authors and offer some perspective on why the utility of this concept remains unresolved.