Role of Fitness in the Metabolically Healthy but Obese Phenotype: A Review and Update
Section snippets
Overall description of the studies reviewed
We found 12 studies in which any of the components of PF were compared between MHO and MAO. The most relevant information from each of these studies is presented in Table 1. In addition, a summary of the characteristics of these studies is shown in Table 2. Surprisingly, 75% of the studies focused exclusively on women20., 21., 22., 24., 26., 27., 28., 29., 30. and only 25% focused on both women and men (no study was focused only in men).31., 33., 34. Likewise, all studies20., 21., 22., 24., 26.
Does PF influence the prognosis of MHO? Current evidence from prospective longitudinal data
From a public health and clinical point of view, the most relevant question is related to the prognosis of MHO individuals when compared with MAO individuals and also when compared with normal-weight individuals. The present review identified only one study, conducted by our group, that explored the role of CRF (no study examining other PF components) in relation with the prognosis of MHO.34 In that study, we observed that when models were not adjusted for CRF, the results suggested that
Proposal of a harmonized definition of the MHO and MAO phenotypes
While reviewing the existing literature on MHO individuals, it became clear that a harmonized definition of the MHO was highly needed. A standardized definition of MHO would increase the comparability of the data, allowing accurate meta-analyses in the future. Based on several facts, we hereby propose a harmonized definition of the MHO and MAO phenotypes (Table 3).
Future directions
In addition to the need of a harmonized MHO definition, several future directions for research have been identified in this review: 1) more investigation is needed for a better understanding of the interrelationship between MHO and cardiorespiratory fit obese phenotypes50; 2) whether the differences in PF between MHO and MAO differ by gender and whether the role of PF in the prognosis of MHO differ by gender are unknown and need to be addressed; 3) there is a need for further study on the role
Conclusions
The studies reviewed suggest that a higher CRF level should be considered a characteristic of the MHO phenotype. Likewise, CRF seems to play a key role in the prognosis of the MHO individuals, yet this statement is based on a single study and future studies are needed to confirm or contrast these findings. In a perfect world, all individuals would be fit and metabolically healthy at any weight.
Acknowledgments
FBO was supported by a grant from the Spanish Ministry of Science and Innovation – MINECO (RYC-2011-09011). CCS is supported by a grant from the Spanish Ministry of Economy and Competitiveness (BES-2014-068829).
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Competing interests: The authors have declared that no competing interests exist.