by Bianca Garilli, ND
As the rise in obesity continues globally, questions remain: do all people with obesity have increased risk of long-term chronic health conditions, or whether is there a subset of individuals who are healthy despite having obesity? In fact, the concept that “not all obesity is created equally” is emerging in the literature1 to describe individuals with obesity but who do not (yet) carry the markers of disease. This phenomenon is commonly referred to as metabolically healthy obesity (MHO).2
MHO is considered to be obesity in the absence of metabolic disorders, including type 2 diabetes (T2D), dyslipidemia, and hypertension. However, inconsistencies in MHO definitions throughout the literature to date creates a challenge to study this concept.1 Researchers have postulated that MHO may not be stable in the long term and that MHO eventually transitions into metabolically unhealthy obesity (MUO) or “unstable MHO”.1-2 New studies indicate key differences may exist between individuals with obesity who go on to develop disease and those who maintain a long-term healthy state.
A recent study published in the Journal of the American College of Cardiology hypothesized that MHO at baseline is not stable and will eventually transition to metabolic syndrome (MetS). To test this theory, 6809 individuals from the Multi-Ethnic Study of Atherosclerosis (MESA) prospective, observational cohort study were studied to determine the joint association between obesity (BMI >30) and MetS with cardiovascular disease (CVD) and mortality across a median of 12.2 years.2 In the MESA cohort, metabolically healthy normal weight individuals were compared to those with MHO.2
Baseline MHO, when compared to metabolically healthy normal weight individuals, was not significantly associated with incident CVD.2 However, nearly 50% of the MHO individuals went on to develop MetS during the follow-up period. This indicates a transition to unstable MHO and significantly increased odds (1.6x greater odds; OR: 1.60, CI: 1.14-2.25) of developing CVD when compared with stable MHO or healthy normal weight individuals.2 Furthermore, MetS significantly mediated the relationship (accounting for 62%) between obesity and CVD.2
The study’s authors concluded: MHO is not stable nor is it a reliable indicator for future CVD risk.2
Why is this Clinically Relevant?
- Previous studies have indicated a subset of MHO individuals exist
- New studies indicate the long-term instability of MHO, and these individuals may have an increased risk of developing MetS and CVD2
- All individuals with obesity, regardless of a “stable” (MHO) or “unstable” (MUO) designation, should begin lifestyle modifications aimed at reducing weight and lowering risk of future chronic disease
Citations
- Jung CH, Lee WJ, Song KH. Metabolically healthy obesity: a friend or foe? Korean J Intern Med. 2017;32(4):611–621.
- Mongraw-Chaffin M, Foster MC, Anderson CAM, et al. Metabolically healthy obesity, transition to metabolic syndrome, and cardiovascular risk. J Am Coll Cardiol. 2018;71(17):1857-1865.
