WASHINGTON (Reuters) - It may be possible to be both fat and healthy, researchers reported on Monday, for at least half of overweight adults, and close to a third of obese men and women, have normal blood pressure, cholesterol and other measures of heart health.

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And being lean does not necessarily protect people, either. Close to a quarter of normal-weight U.S. adults in one study had risk factors for heart disease or diabetes.

“We really don’t know as much about obesity as we think we do,” Judith Wylie-Rosett of the Albert Einstein College of Medicine in New York, who oversaw the study, said in a telephone interview.

“A considerable proportion of overweight and obese U.S. adults are metabolically healthy, whereas a considerable proportion of normal-weight adults express a clustering of cardiometabolic abnormalities,” Wylie-Rosett and Rachel Wildman and colleagues wrote in their report, published in the journal Archives of Internal Medicine.

Wylie-Rosett’s team looked at data on 5,440 men and women who were examined and filled out questionnaires for the National Health and Nutritional Examination Surveys between 1999 and 2004. Most did not exercise very much.

They found just over 51 percent of those who were overweight, and 31.7 percent of those who were obese, had healthy levels of cholesterol, blood sugar, blood pressure and other measures linked to heart disease.

These measures have been shown in many other studies to predict heart attacks, strokes, diabetes and other heart disease, although this particular study did not look at whether people suffered any of these problems.

OBESE YET HEALTHY

More than 23 percent of those who were at a healthy weight, as measured by body mass index, had two or more unhealthy readings, the researchers found.

“Our study shows you can still be healthy even if you are obese,” Wylie-Rosett said.

Her team did not look at people’s diets, but she believes the location of body fat is as important as how much there is. Many studies have shown that having visceral fat, in and among the internal organs, may be more dangerous than having fat thighs or buttocks.

But when Wylie-Rosett’s team measured waist circumference, a common way to estimate visceral fat, more than 36 percent of the obese people with what should have been dangerously large waists had healthy blood test results.

A second study suggested that the liver may be the key.

Dr. Norbert Stefan and colleagues at the University of Tubingen in Germany closely examined 314 people, using magnetic resonance imaging to look at precisely how much body fat they had and where it was.

They also found that obese men and women could have healthy hearts and arteries and suggested that having fat on the liver may be what makes the difference.

“Altogether, 10 percent of the study population and 25 percent of the obese subjects had a high insulin sensitivity phenotype or ‘metabolically benign obesity,’” they wrote in their Archives report.

“Our data suggest that ectopic fat accumulation in the liver may be more important than visceral fat in the determination of such a beneficial phenotype in obesity,” they wrote.

“That’s an area that we are very intrigued with as well,” Wylie-Rosett said,” adding: “If you start stuffing people with calories, it is very much like making pate from goose liver.”

Geese are often force-fed to make their livers fatty and thus more suitable for pate-making.