36 APPLIED PHYSIOLOGY 



Whether fat really restricts heat loss is not so certain. 

 Seeing that it is a highly vascular tissue, it is not quite 

 easy to see why it should, although it seems certainly to 

 be true that lean individuals stand cold badly. We shall 

 return to this point in another chapter. 



In addition to its formation from the fat of the food, 

 body-fat is undoubtedly derived from carbohydrates a 

 fact which is turned to account every day in the treat- 

 ment of obesity. The fat so derived appears to be richer 

 in palmitin and stearin and poorer in olein than fat 

 derived from fats in the food, Whether protein can be 

 used to form fat is a question which is still not definitely 

 settled. Certainly, the amount of fat so derived must 

 be very small. Were it otherwise, the results of the 

 Banting system of treating obesity would not be so 

 satisfactory. 



Of the stages in the destruction of fat in the body we 

 know but little, but they are probably in their initial 

 steps, at least very similar to the cleavage into fatty 

 acids and glycerine which takes place in digestion. 

 The possibility of the production of /3-oxybutyric acid 

 in the course of cleavage is of great interest in connection 

 with the pathology of diabetes. The stages in the pro- 

 duction can be seen from the following formulae : 



CH 3 - CH 2 - CHjj - C0 2 = Butyric acid. 



C 3 H 5 (CH 3 -CH 2 -CH 2 - CO^s = Glyceryl tributyrate, a 



typical fat. 

 H(CH 3 - CH - OH - CHg - CO^ =/S-oxybutyric acid. 



That fats undergo such a transformation as this in 

 diabetes a study of the chemical pathology of that 

 disease seems to show, and it is possible that the change 



