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New research in a large cohort of women demonstrates that obesity is a risk factor for cardiovascular disease (CVD), irrespective of whether the individual remained metabolically healthy over long periods of time.

“There is an ongoing debate regarding whether there is a subgroup of patients with obesity without an increased risk of major chronic diseases such as CVD,” explains author Matthias Schulze. Previous work had indicated that being metabolically healthy might be a transient phenotype in many patients with obesity; however, this theory has not been confirmed by definitive long-term studies, leading Schulze and colleagues to carry out the current study.

The study included 90,257 women from the Nurses’ Health Study who were recruited in 1976 and followed up every 2 years from 1980 to 2010. The women were stratified by BMI category and metabolic health, with ‘metabolically healthy’ being defined as an absence of diabetes mellitus, hypertension and hypercholesterolaemia. At each follow-up, BMI was recalculated and incident cases of CVD (myocardial infarction and/or stroke) were recorded.

As would be expected, the women with obesity who were metabolically unhealthy at baseline or who converted to a metabolically unhealthy phenotype during follow-up had the highest risk of CVD. Interestingly, the researchers found that women with obesity who maintained a metabolically healthy phenotype during the follow-up still had an increased risk of CVD compared with women with a stable normal weight who were metabolically healthy. In addition, most of the women (across all BMI categories) who were metabolically healthy at baseline transitioned to a metabolically unhealthy phenotype during follow-up.

there might be alternative ways to define metabolic health

The authors note that their study is limited by only including women, who were mainly of white European origin. However, “there might be alternative ways to define metabolic health that potentially could identify obese subgroups that are not at increased risk of CVD,” concludes Schulze. “Such alternatives should be explored in more detail.”