The weight of a person is dependent on the balance of the intake and the output of energy. There is, however, no information which explains why some persons are contented with an intake equal to their energy output while others choose an excessive or a deficient intake of food. It is possible that the sensation of satiety is the controlling factor in making this choice. The physiologic reactions which are the components of this sensation have not been fully established. The production of heat resulting from the ingestion of food is well known, and it is conceivable that the sudden change in the rate of production of heat by the body during a meal may bear some relation to the sensation of satiety. The disposition of the heat, particularly its dissipation, may be of importance in this relationship. One factor of the dissipation of heat is reflected in the changes