Food Intake as a Mechanism of Temperature Regulation *

During the conduct of certain studies upon the regulation of energy exchange, two hypotheses have been adopted for testing by experiment. The first of these, viz., that the processes of energy exchange are integrated and regulated by the hypothalamus, has been presented elsewhere, together with data with which it appears to be in agreement.4' 5 The second hypothesis is related to the first, and states that one of the bases upon which this integration is achieved is the effect which each of the four factors of energy exchange has upon body temperature regulation. According to this view, both food and work represent important sources of heat for the organism, and the amount of food eaten or muscular activity undertaken is determined in part by the animal's need for heat and its ability to lose heat to the environment. This second hypothesis implies that food intake should bear a definite relationship to environmental temperature, since the latter is the variable which more than any other determines an organism's need for heat. At a high temperature where loss of heat is difficult, food intake should be low, lest by eating and assimilating food the body acquire more heat than it can dispose of. At a low temperature, food intake should be high because the body can use extra heat in defending itself against hypothermia. It is conceivable, however, that if the temperature is low enough, the animal may not eat enough to supply all of the extra heat it needs, simply because the capacity of the gastrointestinal tract may not be great enough to care for that much food. If this is true, a certain temperature should be found where food intake is maximal, and any further lowering of temperature should not evoke a corresponding rise of food intake.