In past years several objections to the use of a diet high in protein for the diabetic patient have been forwarded. These have fallen into three main groups-first, that in some way protein exerted a specific action, the result of which was to interfere with the mechanism of sugar utilization (1,2,3,4); secondly, that the specific dynamic effect of protein in increasing heat production was wasteful in terms of total energy expenditure and as such should be minimized (1,4,5,6); and, thirdly, that protein constituted a large source of endogenous glucose and therefore should be carefully curtailed in the diabetic diet. The latter is the only one that has in any measure stood the test of time as far as practical diabetic management is concerned (7,8,9). It is our purpose to show that it is an advantage to the diabetic to derive a large part of his total metabolic glucose from protein foods.It is a fact that during the metabolism of protein there occurs a yield of glucose which approximates 50 per cent of the weight of the ingested protein (10,11,12,13,14,15). Janney (16) working with isolated proteins found that the glucose liberated varied from 48 per cent to 80 per cent. It is reasonable to state that 50 per cent represents a good average figure in calculating diets in which the total intake of protein is made up of a mixture of many single proteins.Since protein in the diet represents a large source of glucose, it was decided to compare the blood sugar levels and glycosuria produced by ingestion of equivalent amounts of glucose derived on the one hand from protein and on the other from glucose and carbohydrate foods. The studies were made on fifteen diabetic patients and three normal fourth year medical students.Each subject was maintained aglycosuric for at least two weeks before the study was begun. METHODThe blood sugar level in the postabsorptive state was determined. At this time glucose was absent from all of the urine specimens. A breakfast consisting of 2 grams of protein per kilogram of body weight was given. The source of protein was lean beef from which all visible fat had been removed. This was ground and fried as hamburger steaks, using a minimum of butter in this process. The beef under these conditions contained 5 to 6 per cent of fat and 20 to 22 per cent of protein.The time taken for ingestion of the meat varied from seven to twenty minutes. Blood and urine specimens were collected hourly for eight hours. Timing was begun immediately after the conclusion of breakfast.Blood sugar was determined by the Benedict (17) method and blood urea nitrogen by the Van Slyke (18)

As a rule when the terms, "water balance" or "Cwater exchange," occur in clinical literature, the writer has in mind merely a comparison between the water which enters the body as food and drink with the water which leaves it as urine. Sometimes the water of the stool is also included. *A statement that includes merely these increments of water is inaccurate and liable to be misleading, since it fails to take into account (1) the large amount of water that is evaporated from the skin and lungs; (2) the water that is formed by oxidation of the food; (3) water physically held as part of the protoplasm, but set free when the organism derives some of its energy by burning its own tissues.We propose to describe a system which permits the observer to obtain an accurate account of all the sources and the total amount of water that becomes available for the organism on the one hand; and of the amount of water that leaves the organism on the other hand.In working out a plan for dealing with all the increments of water, it is helpful to think of them under two separate headings: (1) Those that may be measured by standard laboratory methods; and (2) those whose value is obtained indirectly by calculation. The first group includes the water that the subject drinks as such, and the water contained in the food, urine and stool. The second group consists of the water evaporated from the skin and lungs, the water that is a byproduct of the combustion of materials, and water made free when body tissue is burned.

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Heretofore, it has not been possible to measure the heat production of individuals leading their usual lives, due to the unavoidable restrictions necessary to carry out either direct or indirect calorimetry. It is quite obvious that the movements of a subject in a calorimeter are sharply restricted by the capacity of the apparatus and, hence, prevent normal activity. On the other hand, the value of determinations based on indirect calorimetry depends on sampling in such a way that the expired air thus collected is really representative of the period, and there is no way of knowing whether this is the case. Further, the sampling necessarily requires the individual to be at rest for frequent ten minute periods and so disturbs his usual routine. The method which we are proposing is not hampered by either of these two restrictions.In an earlier paper (1) it was pointed out that the insensible loss of weight is roughly proportional to the heat production of the period, provided two sources of error are excluded; namely, first, there must be a proper relationship between the rate of heat production and the environmental conditions, and, secondly, the subject must be transforming a minimal amount of energy to mechanical work. In the previous paper it was also shown that the insensible loss of weight is the resultant of the weight of water lost by evaporation, the weight of exhaled carbon dioxide and the weight of absorbed oxygen. The relationship can be conveniently expressed as an equation:Insensible loss of weight = H20 + CO2 -02.

The medical profession in general, believes that there are two kinds of obese persons-those who have become fat because they overeat or under-exercise; and those composing a second group whose adiposity is not closely related to diet, but is caused by an endocrine or constitutional abnormality.The first apparently scientific support of the hypothesis that obesity was often of endogenous origin, came with the finding that some obese persons had an abnormally low basal metabolic rate, on the basis of body weight. When, however, it was shown that the expenditure of energy is proportional to the surface area and not the weight, it was found that most such persons have a normal basal metabolic rate. However, it is true that there remains a small group of fatpeople whose basal rate is definitely low.Later writers maintained that a common cause of endogenous obesity was to be found in a lessened specific dynamic response to food. But the increase in metabolic rate caused by food is relatively small, so that a method possessed of a high degree of accuracy is needed in order to deal quantitatively with this phenomenon. Our prolonged study of this question has convinced us that the inherent error in the method to date, when it is applied to the human subject, is such that it precludes the possibility of making quantitative statements regarding the specific dynamic response to food in man.Other writers have attributed endogenous obesity to a constitutional anomaly of the cells which somehow lowers the rate of intracellular oxidations.

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