MONDAY, Sept. 11, 2017 (HealthDay News) -- Obese people face an increased risk of heart disease, even if they are free of conditions such as diabetes and high blood pressure, a large new study suggests.
Researchers said the findings, based on 3.5 million British adults, cast doubt on the notion of "healthy obesity."
In recent years, some research has suggested that obesity may not be a heart risk -- as long as a person is "metabolically healthy." That typically means being free from high blood pressure, high cholesterol and type 2 diabetes.
The new findings paint a different picture.
Researchers found that even metabolically healthy obese adults had a heightened risk of developing heart disease or suffering a stroke over the next five years.
"It does not appear that obesity is benign," said Jennifer Bea, a researcher at the University of Arizona Cancer Center who wrote an editorial accompanying the study. Both were published Sept. 11 in the Journal of the American College of Cardiology.
If obesity itself does contribute to cardiovascular trouble, the implications would be wide-reaching. In the United States alone, almost 38 percent of adults are obese, according to the U.S. National Institutes of Health.
There are potential reasons that obesity could directly raise a person's risks of heart disease, according to Bea.
Excess fat, she said, releases inflammatory substances, and chronic low-level inflammation can contribute to artery disease.
But at the same time, the study found, being thin was no guarantee of good health.
About 10 percent of normal-weight people had high blood pressure, high cholesterol or diabetes. And they faced an increased risk of cardiovascular trouble, versus other normal-weight adults.
Bea called that finding "striking" and a wake-up call to people who assume they are healthy because of their jeans size.
"We need to get real," Bea said. That applies to doctors, too, she noted. When patients are thin, some doctors pay less attention to a relatively high cholesterol or blood pressure reading.
For the study, researchers led by Dr. Rishi Caleyachetty of the University of Birmingham in England combed through medical records from 3.5 million adults.
Almost 15 percent were obese and deemed metabolically healthy -- free of diabetes, high blood pressure and high cholesterol. Another 38 percent were of normal weight and metabolically healthy.
Over five years, more than 165,300 people developed a heart or cardiovascular condition.
Compared with normal-weight healthy people, those who were obese and healthy were 49 percent more likely to develop coronary heart disease. (That includes heart attacks or clogged heart arteries that cause chest pain.)
They also had double the risk of heart failure, and a 7 percent higher risk of stroke.
That was with factors such as age, smoking and socioeconomics taken into account.
Dr. Chip Lavie is medical director of cardiac rehabilitation and preventive cardiology at the Ochsner Heart and Vascular Institute in New Orleans.
He said the study was well-done, but also leaves questions open.
A "major limitation," Lavie said, is that the researchers had no information on people's exercise habits or fitness levels.
According to Lavie, past research has found that "fitness is much more important than fatness in predicting [heart] prognosis."
He said he suspects that obese people who were metabolically healthy and fit would have shown little to no increase in their risks -- at least when it comes to coronary heart disease.
As it stood, Lavie noted, "healthy" obese people still had a lower risk of coronary heart disease, versus normal-weight people who had just one metabolic condition.
According to Bea, the message for obese adults is straightforward: "Considering weight loss is probably a good idea."
Of course, that's easier said than done. Many people who shed weight often put it back on, Bea said.
And no one wants people to give up on healthy habits just because the number on the scale hasn't plummeted, Bea said.
"Being physically active is definitely better than not being active," she said. "Eating a healthy diet is better than not eating a healthy diet."
That same principle, she added, also applies to normal-weight people.
The U.S. National Institutes of Health has advice on weight control.