Increased awareness of the changes in body weight associated with burn therapy can improve patient care during resuscitation as well as convalescence. Weight loss in the later stages of burn injury reflects a large resting energy expenditure thought to be related to evaporative heat loss. The difficulties involved in balancing the caloric equation by increased intake have led to efforts to reduce evaporative losses. A review of recent studies relating vaporizational losses and resting metabolic expenditure shows a more complex relationship than had been previously suspected. Despite the well-documented clinical importance of evaporative cooling, burn hypermetabolism is evidently the result of multiple mechanisms and will require more than reduction of evaporative water loss if weight loss is to be minimized.