May 31 (UPI) -- Even if she has been metabolically healthy for decades, an obese woman still has a higher risk of developing cardiovascular disease compared to women of normal weight, according to a study.
Researchers studied data from 90,257 women in the United States from 1980 to 2010 for cardiovascular disease. Their findings were published Wednesday in the The Lancet Diabetes & Endocrinology journal.
The researchers found obesity is a risk factor for cardiovascular disease even without the presence of common metabolic diseases such as high blood pressure or type 2 diabetes. They also found there's a strong likelihood most metabolically healthy women eventually become metabolically unhealthy even if they have a normal weight.
"Our large cohort study confirms that metabolically healthy obesity is not a harmless condition, and even women who remain free of metabolic diseases for decades face an increased risk of cardiovascular events," research leader Dr. Matthias Schulze, of the German Institute of Human Nutrition Potsdam-Rehbruecke in Nuthetal, said in a Lancet news release. "What's more, we observed that most healthy women are likely to develop type 2 diabetes, high blood pressure, or high cholesterol over time, irrespective of their BMI, putting them at much higher risk for cardiovascular disease."
Obesity is defined as a body mass index -- or BMI -- of more than 30. But researchers noted that as many as a third of obese people might be metabolically healthy.
The researchers examined the association between obesity and cardiovascular disease from the Nurses' Health Study, which tracked the health of female nurses from 30 to 55.
Participants were divided into groups by BMI category.
Metabolic health was defined as the absence of three metabolic risk factors -- type 2 diabetes, high blood pressure and high blood cholesterol. Participants were sent questionnaires every two years to update their BMI and metabolic health status, assess their lifestyle, health behavior and medical history.
Adjusted factors included age, diet, smoking status, physical activity, alcohol consumption, ethnicity or race, highest education level, menopausal status, aspirin use and family history of heart attack or diabetes.
In an average follow-up of 24 years, there were 6,306 new cases of cardiovascular disease, including 3,304 heart attacks and 3,080 strokes.
"Long-term maintenance of metabolic health is a challenge for overweight/obese, but also for normal-weight women," Schulze said. "Our findings highlight the importance of preventing the development of metabolic diseases, and suggest that even individuals in good metabolic health may benefit from early behavioral management to improve their diet and increase physical activity in order to guard against progression to poor metabolic health."
Metabolically unhealthy women with normal weight were about 2.5 times more likely to develop cardiovascular disease compared with normal weight women with no metabolic problems. And those who were metabolically healthy and obese were at a 39 percent higher risk of cardiovascular disease.
Over 20 years, women converted to unhealthy phenotypes -- at an 84 percent clip among metabolically healthy obese women and a 68 percent rate among normal weight metabolically healthy women.
And even women who maintained metabolically healthy obesity still had a 57 percent higher risk of developing cardiovascular disease compared to normal weight metabolically healthy women.
The authors noted the study included mainly women of European descent.
"Drastic efforts are needed to prevent obesity in the first place and, especially, to prevent conversion to more severe degrees of obesity and the metabolic syndrome," Carl Lavie, of the University of Queensland School of Medicine, wrote in an accompanying commentary. "Public health policies aiming to increase cardiorespiratory fitness through physical activity and exercise will further contribute to improve people's health. It is prudent to remind ourselves that an ounce of prevention is better than a pound of cure."