Some obese individuals do not appear to have an increased risk for heart disease, while some normal-weight individuals experience a cluster of heart risks, according to two reports in the August 11/25 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.1
“The prevalence of obesity is increasing worldwide, and this epidemic is accompanied by a high incidence of type 2 diabetes mellitus and cardiovascular disease,” the authors write as background information in one of the articles. Research indicates that in addition to overall obesity, the way body fat is distributed may influence risk for heart disease and diabetes. For instance, individuals with fat within the abdominal cavity—estimated by measuring waist size—appear to be at higher risk for insulin resistance (a pre-diabetic condition that occurs when the body fails to respond to the hormone insulin) and for having an unhealthy cardiovascular risk profile.
In one study, Norbert Stefan, M.D., and colleagues at the
Those in the overweight and obese groups had more total body and visceral fat than those at a normal weight, and there was no difference between obese groups. However, obese individuals with insulin resistance had more fat within their skeletal muscles and their livers than obese individuals without insulin resistance. In addition, those who were insulin-resistant had thicker walls in their carotid arteries, an early sign of atherosclerosis (narrowing of the arteries, a heart disease risk factor).
Individuals in the obese–insulin sensitive group did not differ from the normal-weight group in insulin sensitivity or artery wall thickness, the authors note. “In conclusion, we provide evidence that a metabolically benign obesity can be identified and that it may protect from insulin resistance and atherosclerosis,” they write. “Furthermore, our data suggest that ectopic [misplaced] fat accumulation in the liver may be more important than visceral fat in the determination of such a beneficial phenotype in obesity.”
In a second study, Rachel P. Wildman, Ph.D., of the Albert Einstein College of Medicine,
“These data show that a considerable proportion of overweight and obese
Both studies attempt to improve the understanding of obesity, making it a more useful tool for predicting which patients will develop cardiovascular disease, writes Lewis Landsberg, M.D., of the
“Both reports emphasize the benign nature of fat accumulation outside the abdomen,” he writes. “In both studies, the detrimental effect of visceral fat accumulation and its surrogate, waist circumference, were clearly demonstrated, confirming older studies showing that waist circumference is a risk factor even in normal-weight individuals.”
The message for practicing clinicians is that calculating body mass index and measuring waist circumference are valuable tools in assessing cardiovascular risk in overweight and obese patients, Dr. Landsberg concludes.
- Arch Intern Med. 2008;168:1609-1616 and 1617-1624.
- Arch Intern Med. 2008;168:1607-1608.