The AIDS wasting syndrome was originally viewed as inevitable, cytokine driven and progressive. Research in animal models and AIDS has defined a more complex pathway. Wasting is not inevitable in HIV disease. Rather wasting in due to complications. Rapid wasting is usually due to secondary infection; slower wasting is often a sign or gastrointestinal disease. Prior theories proposed that wasting was caused by cytokine induced disturbances in metabolism. However, cytokines can induce such metabolic changes without inducing wasting. In AIDS, the classic changes in lipid metabolism are due to interferon alpha, but show no relation to wasting. Resting energy expenditure REE is also not sufficient to cause wasting. In secondary infection, anorexia leads to weight loss; the inability to compensate normally for decreased intake by decreasing REE accelerates negative energy balance. Failure to fully recover from bouts of weight loss leads to debilitation and wasting. Therapies are needed to increase weight and rebuild muscle mass. Others should be developed to blunt losses during infection and gastrointestinal disease.

Cachexia/COMPLICATIONS/METABOLISM/*PHYSIOPATHOLOGY/THERAPY Cytokines/*METABOLISM Energy Metabolism HIV Infections/*COMPLICATIONS/METABOLISM Human Lipids/METABOLISM ABSTRACT

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