Metabolically healthy obesity does not guarantee clean bill of health

Research has found conflicting evidence about whether it is possible for some obese people to avoid health complications that increase the risk of metabolic diseases. These complications can include high blood pressure, high blood sugar, insulin resistance and low levels of high-density lipoproteins, the "good" form of cholesterol that reduces heart disease risk. Past studies have found as many as 30 percent of obese people may be metabolically healthy.

"Unfortunately, our findings suggest metabolically healthy obesity is not a benign condition," said the study's corresponding author, Carlos Lorenzo, MD, of the University of Texas Health Science Center at San Antonio, Texas. "Regardless of their current metabolic health, people who are obese face an increased risk of developing cardiovascular disease and diabetes in the future."

Researchers analyzed prospective data from the San Antonio Heart Study, a population-based study of Mexican Americans and Caucasians, to assess incidence of diabetes in 2,814 participants and cardiovascular disease incidence in 3,700 participants. The SAHS study followed up with participants for a period lasting between six and 10 years. The analysis examined whether the risk of developing diabetes or heart disease was different for normal weight people who had at least two metabolic conditions or metabolically healthy obese people.

To determine metabolic health, researchers examined whether subjects had elevated blood pressure, elevated triglyceride and blood sugar levels, insulin resistance and decreased HDL cholesterol. People who had none or only one of the characteristics were classified as metabolically healthy.

The analysis found that increased body mass index was linked to an elevated risk of developing diabetes. Normal weight people who had multiple metabolic abnormalities also faced an increased risk of developing diabetes. Both groups faced an elevated risk of cardiovascular disease after taking into account demographics and smoking behavior.

"Our data demonstrate the importance of continuing to monitor for diabetes and cardiovascular disease in both people with metabolically healthy obesity and those who have metabolically abnormalities despite being a normal weight," Lorenzo said. "If physicians and patients are too complacent about assessing risk, we can miss important opportunities to prevent the development of chronic and even deadly conditions."