KLEIBEB 



to a lack of capacity in their G. I. tract for the extra food that is 

 needed, or is it due to some other factor? I would like to hear 

 Dr. Hart's opinion on this eventually, but from the data that Dr. 

 Vaughan and I have accumulated withdietsof a high caloric density, 

 it would seem that the capacity of the G. I. tract is not the limiting 

 factor. You can give them plenty of calories but they will still not 

 eat enough to gain weight at the same rate as their controls. Even- 

 tually, however, they will be able to increase their food consump- 

 tion, so that they can gain weight. It has been my feeling that the 

 reason it takes a while for the cold- exposed animal to acquire the 

 capacity to utilize more food and thus to gain weight is that he is 

 not initially able to metabolize food material at a fast enough rate 

 to supply all of his energy needs. Until he builds up an enzyme capa- 

 city to do this, his growth is going to lag behind the control animal. 



HART: 1 would be very surprised if you could, by overfeeding 

 an animal, increase its capacity to oxidize the material. In other 

 words, the appetite would be regulated by internal mechanisms 

 adjusted to the oxidative capacity of the animals and by pushing food 

 in you are not going to change this. 



HANNON: In our studies we compared the food consumption and 

 growth of rats that were maintained on a high carbohydrate diet 

 with rats that were maintained on a high fat diet. It was found that 

 the group subsisting on carbohydrate consumed much greater bulk 

 of food but the same number of calories as the group subsisting on 

 fat. 



Apparently their ability to utilize the calories was the limiting 

 factor, not the ability to get calories into the digestive system. 



HART; Did the carbohydrate or the fat diet have any particular 

 advantage? 



HANNON; Not as far as we could see. 



KLEIBER: Yes, I think the limiting capacity is not the capacity 

 of the volume. Adolph showed this when he diluted diets with clay 

 and other kinds of inert matter. His rats took in and digested as 



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