The body weight is undoubtedly one of our most valuable indexes of nutrition and indicates clearly, when determined over a long period, the balance between the energy supplied to the body in the form of food and the total energy expended as heat and muscular movements. As exophthalmic goiter is one of the few conditions in which the basal metabolism is characteristically elevated, the relation between the food intake, energy expenditure and body weight in this disease should be of considerable interest. It is well known that every normal individual expends a definite amount of energy depending on sex, age, height, weight, food intake and muscular activity. To provide for this an equal number of calories in the form of food must be ingested or the individual will consume his own tissues and a loss in body weight will follow. If a quantity of food in excess of the energy