New study challenges concept of ‘healthy obesity’

Obese adults who display no signs of CVD appear to have a significantly higher prevalence of coronary artery calcification compared with normal-weight adults.

“The risk of cardiovascular disease among obese individuals without obesity related metabolic abnormalities … is controversial,” researchers wrote in the Journal of the American College of Cardiology.

The current data are from a subanalysis of the Kangbuk Samsung Health Study in South Korea. Researchers evaluated 14,828 metabolically healthy adults aged 30 to 59 years without known CVD. “Metabolically healthy” was classified as the presence of no components of the metabolic syndrome and a homeostasis model assessment of insulin resistance (HOMA-IR) <2.5. All participants underwent examination between 2010 and 2012 that included the estimation of coronary artery calcium (CAC) scores via CT. The cohort had a mean BMI of 23 kg/m².

The prevalence of coronary calcification was higher among metabolically healthy obese participants compared with metabolically healthy normal-weight participants. Multivariable analysis indicated a significant association between elevated CAC score and obesity (CAC score ratio=2.26; 95% CI, 1.48-3.43 for obese vs. normal weight). Further analysis revealed that adjustment for metabolic risk factors eliminated the significance of this association, particularly after adjustment for LDL cholesterol (CAC score ratio=1.24; 95% CI, 0.79-1.96 for obese vs. normal weight).

The observed links between obesity and CAC were not influenced by age, sex, exercise level, tobacco or alcohol consumption or Framingham risk score.

“These findings provide strong support to the hypothesis that [metabolically healthy obesity] is not a harmless condition,” the researchers said.

“Furthermore, the association between [metabolically healthy obesity] and CAC scores was largely mediated by residual levels of cardiometabolic risk factors, suggesting that the concept of [metabolically healthy obesity] may be an artifact of the cutoffs used to define metabolic abnormalities and of the parameters included in the definition of [metabolically healthy obesity]. As a consequence, physicians should adequately address the increased risk of CVD in [metabolically healthy obese] individuals, in addition to counseling them about healthy weight and lifestyle,” they said.

The current study contributes to the argument that there is no form of “healthy obesity,” Rishi Puri, MBBS, from the department of cardiovascular medicine at the Cleveland Clinic Coordinating Center for Clinical Research, wrote in an accompanying editorial.

“There is still much for us to learn about obesity and the underlying molecular mechanisms of obesity-related organ disease,” Puri wrote. “… The omics revolution, coupled with vascular imaging, is likely to yield tremendous insight into factors promoting CVD across a variety of population subsets, with the obese population being a primary target for such investigations. This will foster the development of more specific and targeted therapies for tackling obesity. But first we must simply accept obesity as a disease, and consider no level of obesity to be healthy.”

For more information:

Chang Y. J Am Coll Cardiol. 2014;doi:10.1016/j.jacc.2014.03.042.

Puri R. J Am Coll Cardiol. 2014;doi:10.1016/j.jacc.2014.03.043.

Disclosure: The researchers and Puri report no relevant financial disclosures.