PCM can be usefully considered in terms of edematous (kwashiorkor-like) and nonedematous (marasmic) forms, as long as the limitations of the traditional terms are kept in mind. The body composition of subjects with undernutrition, or total starvation, both appear to maintain an extracellular fluid volume at a normal level, which increases as a percentage of the shrinking body weight. This is in contrast to patients with hospital malnutrition, in whom there is often an absolute increase in the extracellular volume while the body cell mass is shrinking. Data from the starvation literature suggest that the adult subject must gain approximately 10% of his or her body weight as extracellular expansion before edema is clinically evident. Preliminary evidence indicates that the hospitalized patient with the edematous form of malnutrition is at greater risk for complications and death when undergoing an operation, or requiring intensive care. The depleted patient who shows a rise in a depressed serum albumin after 7 to 10 days of TPN will have an improved prognosis when undergoing the stress of an elective operation. This improvement appears to be more the result of decreasing the expanded extracellular fluid volume than achieving a major increase in protein stores. The severely catabolic patient, particularly during episodes of major infection, can be expected to benefit by a nutritional intake that is carefully designed to provide calorie and nitrogen equilibrium. Nutritional intake high enough to guarantee positive balances of calories and nitrogen should be delayed until the acute catabolic stimulus has subsided, at which time the nutritional objective is to rebuild lost tissue.