Seventy-six patients with closed head injuries alone were studied to define the relation between the severity of the head injury and secondary alterations of general metabolism. The effect of metabolic changes on neurological outcome and the importance of nutritional support on nutritional status and neurological outcome were also evaluated. Using a powerful statistical tool, convergence analysis, it was possible to take into consideration the effects of a number of confounding factors that obviously affected general metabolism. Most of the patients were hypermetabolic for prolonged periods. In addition, many did not receive even basal requirements of calories or protein for many days. Despite this, their outcomes were determined by their initial neurological status and the amounts that they were fed, admittedly relatively modest, did not influence their courses. Despite such feedings, their visceral protein levels, which often dropped initially, rose toward normal levels, indicating effective adaptation. Indeed, it could not be shown that these patients developed complications of malnutrition such as infections. However, it will require a sophisticated randomized clinical trial of vigorous intravenous hyperalimentation to determine whether this complex, dangerous, and expensive therapy is helpful for severely head-injured patients.