This report consists of three discrete, but interrelated, parts: the first contains a description of the respiratory metabolism of rats with hypothalamic hyperphagia; the second deals with the induction of unusual metabolic patterns in normal, intact rats by the alteration of their feeding habits; andthe third is concerned with the site of conversion of carbohydrate to fatty acids in the animal body. The finding of uncommonly high respiratory quotients (RQ's) after glucose administration in rats with symmetrical hypothalamic lesions led to the discovery that similarly high RQ's are exhibited by rats trained to eat their entire day's ration of food in a short time. Subsequent study of this phenomenon demonstrated the feasibility of investigating the conversion of carbohydrate to fatty acids in the rat by the technic of comparing the respiratory exchange of normal animals with that of" trained" ones. Finally, information gained from this method of studying fatty acid synthesis proved to be useful in an analysis of the mechanisms involved in the development of hypothalamic obesity, and of the metabolic repercussions of established obesity on the organism.

Material and methods Adult albino rats of the Yale and Sprague-Dawley strains were used. Respiratory exchange was determined by means of the Haldane open-circuit method during a period of from 2 to 3 hours in the intact animals and of 3 to 4hours in the eviscerate preparations. Blood and urine sugar were estimated according to methods previously cited by Brobeck et al. 2 Two dietswere employed: Purina Fox Chow (protein 18 per cent, fat S per cent, carbohydrate absorbed as glucose 68 per cent) and a synthetic mixture which contains sucrose 70 per cent, casein 15 per cent, brewers'