CHAPTER IV 



THE QUESTION OF THE CONVERSION 

 OF FAT TO CARBOHYDRATE 



In contrast to the extensive experimental evidence of the transformation of 

 carbohydrate to fat, the reverse change, namely that of fat — > carbohydrate, 

 can take place only to an extremely limited extent. In fact, until stud- 

 ies were available, showing the result of the use of isotopes, there was no 

 clear-cut proof of this transformation which could not be matched by 

 equally convincing data which indicated the opposite conclusion. Few fields 

 in science have given rise to such acrimonious debate and have served as the 

 basis for such a large proportion of polemic reports as the question of 

 whether or not fat can be converted to carbohydrate. 



The acceptance or rejection of the concept that fat can be converted to 

 carbohydrate has largely been associated with the hypothesis of the cause of 

 diabetes. Investigators who accept the "overproduction" theory argue 

 that hyperglycemia and glycosuria, which occur in diabetes mellitus, result 

 from an increased production of sugar from fat. On the other hand, the 

 advocates of the "non-oxidation" theory of diabetes are of the opinion 

 that glucose accumulates because of an impaired utilization of carbohy- 

 drate. Macleod^ advocated the "overproduction" theory, while Lusk^ vigor- 

 ously denied the possibility that such a change obtains. Although the more 

 recent evidence based upon isotope studies has indicated that some transfer 

 of fatty acid carbon to glucose does occur, equally convincing data indicate 

 that fatty acids do not increase the total carbohydrate^"^" availal)le to the 

 organism. A number of reviews were published before the advent of the 



1 J. J. R. Macleod, The Fuel of Life, Princeton Univ. Press, 1928. 



2 G. Liisk, Science of Nutrition, 4th ed., Saunders, Pliiladelphia, 1928, ])p. 642, 644. 



5 W. C. Stadie, Physiol. Revs., 25, 395-441 (1945). 



■• H. B. Richardson, Physiol. Revs., 9, 61-125 (1929). 



6 T. M. Carpenter, /. Nutrition, 4, 281-304 (1931). 



6 H. C. Geelmuvden, Ergeh. Physiol., 31, 1-95 (1931). 

 ^ M. Dann, Yah J. Biol. Med., 5, 359-372 (1932-1933). 



8 H. H. Mitchell, J. Nulrition, 6, 473-491 (1933). 



9 S. So.skin, Endocrinology, 26, 297-308 (1940). 

 '0 S. Soskin, Physiol. Revs., 21, 140-193 (1941). 



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