Last Updated: 2002-09-30 12:01:29 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Although obesity is a risk factor for heart disease, the place where a person stores his or her excess weight may be a more important variable, two new studies suggest.

According to Italian researches, men with a "beer belly," known medically as central obesity, maybe more likely to develop high blood pressure than their peers who store their weight in other areas. Their study found that this pattern of weight gain was associated with elevated blood pressure regardless of body mass index (BMI) and insulin resistance, a condition in which a person loses his or her ability to respond to this key blood sugar-regulating hormone. BMI is a measure of weight in relation to height used to gauge obesity.

The findings may help to explain the link between obesity and metabolic syndrome, a cluster of conditions that include high blood pressure, cholesterol and insulin levels. Left untreated, the syndrome, also called insulin resistance syndrome or syndrome X, can progress to diabetes and heart disease.

"These results provide supportive evidence for the need to reduce overweight and ameliorate insulin sensitivity, both by caloric restriction and by increased physical exercise," Dr. Alfonso Siani from the National Research Council in Avellino, Italy, and colleagues write.

Their study included more than 700 men aged 25 to 75 who were not taking blood pressure-lowering medication. The researchers measured blood glucose and insulin levels after an overnight fast, calculated BMI and took three different blood pressure readings. Abdominal circumference, a marker of central obesity, was determined by measuring the waist in relation to the hips.

Blood pressure rose in tandem with BMI, age, and higher waist-to-hip ratios, report researchers in the September issue of the American Journal of Hypertension. Blood pressure was also associated with higher insulin levels after subjects consumed a sugar-filled drink.

"In middle-aged men, a central distribution of body fat is associated with increased blood pressure, independently of body mass index and insulin resistance, thus suggesting a key role of central adiposity in the full expression of the 'metabolic syndrome,'" the researchers conclude.

The findings are supported by the results of a second study published in the October issue of the American Journal of Clinical Nutrition. In this report, researchers assessed the relationship between waist circumference and heart disease risk factors associated with obesity in more than 9,000 adults.

Waist circumference was found to be a more sensitive measure of heart disease risk factors than BMI, as it more closely correlated with elevated LDL ("bad") cholesterol, high blood pressure, elevated blood glucose (sugar) and lower levels of HDL ("good") cholesterol.

"Waist circumference...may be a stronger predictor than BMI for the identification of metabolic and cardiovascular disease-associated risk factors," Dr. Steven B. Heymsfield from Columbia University in New York City and colleagues conclude.

SOURCE: American Journal of Hypertension 2002;15:780-786; American Journal of Clinical Nutrition 2002;76:743-749.

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