Studies Refine Obesity's Risk for Heart Troubles

Monday, August 11, 2008; 5:00 PM

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MONDAY, Aug. 11 (HealthDay News) -- Some obese people don't seem to be at increased risk for heart disease, while some normal-weight people have a number of heart disease risk factors, according to two studies.

In the first study, German researchers analyzed 314 people, ages 18 to 69, and divided them into four groups: normal weight, overweight, obese but still sensitive to insulin, and obese with insulin resistance.

People in the overweight and obese groups had more total body and visceral fat (abdominal fat around the organs) than those with normal weight. But obese people with insulin resistance had more fat within their skeletal muscles and their livers than obese people without insulin resistance. Obese people with insulin resistance also had thicker walls in the carotid arteries, an early sign of narrowing of the arteries -- a condition called atherosclerosis.

Insulin sensitivity and artery wall thickness were the same in obese people without insulin resistance and in normal-weight people.

"In conclusion, we provide evidence that a metabolically benign obesity can be identified and that it may protect from insulin resistance and atherosclerosis," Dr. Norbert Stefan and colleagues at the University of Tubingen wrote. "Furthermore, our data suggest that ectopic (misplaced) fat accumulation in the liver may be more important that visceral fat in the determination of such a beneficial phenotype in obesity."

The study was published this week in the journal Archives of Internal Medicine.

In another study in the same issue of the journal, U.S. researchers assessed body weight and cardiometabolic abnormalities (including high blood pressure, elevated triglycerides, and low levels of "good" high-density lipoprotein cholesterol) in 5,440 adults who took part in the National Health and Nutritional Examination Surveys between 1999 and 2004.

People with none or one abnormality were considered metabolically healthy, while those with two or more abnormalities were metabolically abnormal.