If obese people are metabolically healthy—that is, if they maintain desirable blood pressure, cholesterol and blood sugar levels, for instance—do they need to worry about their excess weight? Some experts say no. But research on this notion of “benign obesity” has been inconsistent, and several recent analyses have thrown cold water on it.
In a review in the Annals of Internal Medicine, for instance, Canadian researchers looked at studies lasting at least 10 years and found that metabolically healthy obese adults were significantly more likely to have a heart attack or stroke or to die prematurely than their metabolically healthy normal-weight counterparts. Merely being overweight (not obese) but metabolically healthy did not increase the risk. Still, being metabolically unhealthy tripled the risk in all weight categories, even normal weight. Weight categories are based on the body mass index, or BMI.
Similarly, a large Danish study in JAMA Internal Medicine found that overweight or obese people were at increased risk of heart attacks even if they were metabolically healthy. Being overweight but metabolically healthy increased the risk by 24 percent, while being obese did so by 88 percent, compared to metabolically healthy normal-weight people. As in the previous study, being metabolically unhealthy greatly increased the risk in all weight groups.
Bottom line: As the editorial in JAMA Internal Medicine concluded, these findings “add important new evidence to counter the common belief in the scientific and lay communities that the adverse health effects of overweight are generally inconsequential as long as the individual is metabolically healthy.”