Loss of lean body mass in HIV-positive men linked to immunological processes

Men with HIV may continue to lose lean-body mass without overall loss of weight, even if successfully treated with HAART due to an immunological process, according to a study published in the July 2002 edition of the American Journal of Physiology, Endocrinology and Metabolism.

Loss of lean body mass, without loss in overall body weight, a condition called cachexia, can adversely affect a person's ability to function and recover from injuries and illnesses. It has been observed in patients with HIV, even when successfully treated with HAART. Whilst AIDS wasting in the pre-HAART ear was predominantly caused by reduced calorie intake and diarrhoea, weight loss in people receiving HAART is more subtle and less well understood.

Studies have revealed that in patients with rheumatoid arthritis, immunological processes involving the excess production of tumour necrosis factor alpha (TNFa) and cytokines, spur cachexia and increase the resting energy expenditure.

To see if a similar process was involved in cachexia among people with HIV, investigators examined blood samples and changes in body composition in 166 HIV-positive men between May 1995 and August 1998. The average age of the study participants was 41, 63% had had an AIDS defining illness and 43% were being treated with HAART.

The body composition of the study participants was measured on each visit to the clinic and resting energy expenditure was measured after a four hour fast. A 20ml sample of blood was subjected to immunological analysis and CD4 and viral load tests performed. Levels of testosterone were also measured. Study participants were also asked about their daily food intake and exercise habits.

Investigators found that over an eight month period, trial participants lost an average of 0.02kg (range -12.2kg to +8.8kg) of lean body mass and experienced an average increase of resting calorie expenditure of 6.8 cal per day. In 17% of people the increase in resting calorie expenditure was above 200 kcal per day without any corresponding increase in body weight.

Changes in immunological processes and their interaction with free-testosterone production predicted the loss of lean body mass and increase in resting calorie expenditure.

The investigators conclude that cachexia is likely to be a continuing characteristic of HV infection in men, even if HAART is successfully administered, and recommend that anabolic steroids and exercise regimens be considered for people with severe lean body mass loss.