A study presented at the annual meeting of the Infectious Diseases Society of America showed that overweight and obese HIV-positive participants had lower CD4 (white blood cell) counts than their normal weight counterparts.

At the meeting, held October 29-November 1 in Philadelphia, primary investigator Dr. Nancy Crum-Cianflone indicated that the point of her study was to evaluate specific effects of obesity on the immune systems of HIV-infected individuals.

Obesity is known to have negative health consequences, including diabetes, heart disease, and certain cancers. A person may become obese due to genetic and environmental factors, as well as from drug side effects. Proper eating habits and regular exercise help to maintain healthy body weight.

A person is considered obese when his or her body mass index exceeds 30 kg per meter of height squared. Normal weight is defined as between 18.5 and 24.9 kg per meter squared.

Crum-Cianflone and her colleagues found that obese HIV patients were more likely to have lower CD4 counts than those who were of a normal weight. Furthermore, obese participants were also more likely to have lower counts than the overweight group.

Specifically, CD4 counts increased post-treatment by 69 cells per microliter of blood in obese patients, compared to a greater increase of 103 cells per microliter of blood in persons of appropriate weight.

Crum-Cianflone noted that it is unclear why obesity has this effect. She proposed that standard drug dosing may not be sufficient for obese patients, or extra weight may limit the effects of antiretroviral drugs.

In addition, participants who were underweight had CD4 lower counts, highlighting the importance of maintaining an appropriate weight.

In the past, health professionals were concerned with wasting in HIV-positive individuals. Wasting refers to the process by which a debilitating disease such as AIDS causes muscle and fat tissue to wither away. However, this study shows that obesity is also a problem.

Crum-Cianflone suggests that weight-monitoring programs should be included in HIV care to ensure maximal health of HIV-positive individuals.

Of the 1,119 participants in seven HIV clinics across the country, 39 percent were overweight, nine percent were obese, and one percent was underweight.

Most of the participants were male (96 percent). Forty-four percent were Caucasian, 41 percent were African American, and 15 percent were of other races.

The study was conducted by the U.S. Military and also received funding from the National Institutes of Health.

For more information, please read the article on AIDS.gov and on the European AIDS Treatment Group Web site.