326 FOOD INGESTION AND ENERGY TRANSFORMATIONS. 



over the last fasting day. This increase was independent of whether 

 the fuel value of the food was considerably above or below that required 

 for maintenance on the fasting day. Second, with the same individual 

 the reaction to food was apparently by no means constant, for in the 

 first two experiments with S. A. B. there was little, if any, increment due 

 to food, although in the second experiment the fuel value of the food 

 was from 400 to 500 calories above fasting maintenance requirements. 

 On the contrary, at the end of the 7-day fast, food with a fuel value of 

 200 calories greater than the heat production of the last fasting day 

 produced an increase of 200 calories in the total heat production. In 

 all probability the length of the fast, the influence upon the basal metab- 

 olism of the fasting per se, the fuel value of the intake, and the propor- 

 tion of protein in the intake are in some way related. In all of the 

 experiments reported in this table there was an actual loss of nitrogen 

 during the food experiment, as there was not sufficient protein in the 

 intake to compensate for the outgo. 



Finally, although the evidence is somewhat meager, it is of funda- 

 mental importance to consider the relationship between the ingestion 

 of food and the basal metabolism after fasting, with a view to consider- 

 ing the possibilities of lowering the basal metabolism by inanition or 

 undernutrition, and then maintaining the metabolic level on smaller 

 food requirements than those ordinarily obtaining. For example, in 

 the first experiment with S. A. B., we have a heat production on the 

 second fasting day of 1,844 calories. On the fourth day this was 

 reduced to 1,606 calories. The fuel value of the food ingested was 

 1,698 calories, which was essentially that required for maintenance. 

 It is quite clear, therefore, that we deal here with a maintenance, at 

 least temporarily obtaining, at a level of 150 or more calories below 

 that on the second fasting day. The fact that in the second experiment 

 with S. A. B. the 2,078 calories in the food did not cause a pronounced 

 rise in the metabolism is likewise of great significance, for by 5 days of 

 fasting the basal metabolism was lowered over 300 calories, and the 

 ingestion of an excess amount of food over requirements on the next 3 

 days increased the heat production only about 100 calories above the 

 last fasting day. On the other hand, these conclusions are considerably 

 weakened by the course of the metabolism in the last experiment with 

 S. A. B., in which food with a fuel value a little above the fasting 

 requirements produced an increment of 200 calories, raising the metab- 

 olism to that on the first three or four fasting days. 



These experiments are extremely suggestive in their bearing on the 

 question of a basal metabolism lowered either by fasting or by prolonged 

 undernutrition. They should be followed by observations on the 

 influence of very moderate or barely maintenance diets to note if the 

 tendency of the basal metabolism is to return to the initial value or to 

 maintain the lowered value found as a result of undernutrition or 



