Wasting in HIV infection and AIDS.

AIDS wasting is not characterized by a single pathophysiological process but by a variety of processes that operate at different times. Acute wasting tends to be associated with secondary infections; chronic wasting is associated with gastrointestinal disease. Although resting energy expenditure is increased, total energy expenditure is reduced in individuals who are losing weight and it is usually reduced intake that commonly drives wasting. However, reduced intake is not an adequate explanation for the metabolic abnormalities that are seen in HIV infection. In particular, protein metabolism and lipid metabolism are abnormal, possibly representing inappropriate utilization of substrates. The response to nutrition may be impaired, particularly in terms of accrual of lean tissue but nutritional support may prolong survival. The impact of protease inhibitors on wasting in HIV infection is yet to be fully ascertained but despite antiviral therapy it seems that wasting is likely to remain a problem at least in some patients.