Current issues in the identification and treatment of metabolically healthy but obese individuals

A unique subset of obese individuals who appear to be protected from the development of metabolic disturbances has been identified in the medical literature and is termed metabolically healthy but obese (MHO). Part of the issue is that there are no clear accepted criteria on the definition of MHO and the biological mechanisms to explain this phenotype are still unknown which render findings and/or conclusions difficult to interpret and making the application of this concept difficult in clinical practice. With the current definitions, the true prevalence of the MHO phenotype in the general population varies widely from approximately 3-57% of obese adults. In several prospective studies, the MHO individual has been associated with a similar risk of developing type 2 diabetes, cardiovascular disease and mortality when compared to healthy normal weight subjects; however, there is evidence to refute this concept. Furthermore, the current evidence cannot confirm that MHO subjects are permanently protected from the risk of developing metabolic disturbances associated with obesity. Currently, no standard practice guidelines for the treatment of MHO can be proposed, however, a regular surveillance of the waist circumference and cardio-metabolic risk factors such as elevated triglycerides, glycaemia, HOMA, C-reactive protein and low HDL, as well as the prevention of any further weight gain seem to represent the most prudent and sound attitude in the management of MHO subjects.