The reasoning by means of which the good results of this abstemious diet, and especially of the low protein intake, were accounted for is interesting indeed. A diminished intake of protein leads to a decreased formation of crystalline waste products, such as acid potassium phosphate, uric acid and the purin bases and other end-products of nitrogen metabolism. These are in part responsible for the sensation of fatigue when they accumulate in the blood. The energy of work comes not from the degradation of muscle substance, but from the combustion of non-nitrogenous food-stuffs such as sugar and fat, and it is not, therefore, necessary to take large amounts of protein food for the purpose of replacing the wear and tear quota, for the latter is but of small magnitude even in severe work. Protein stimulates body metabolism in general, and hence will lead, when taken in excessive amounts, to a rate of metabolism far in excess of the normal amount which results from a diet lower in this factor. This augmentation in the metabolism of the body tissues leads to a waste of energy-yielding substances which might otherwise be conserved for useful expenditure.

It was noted by Dr. Chittenden that while on the low protein diet there was not a single day during the nine months when his urine was turbid, whereas on a rich protein diet it was necessary to take a large amount of water in order to prevent the kidneys from becoming clogged. It was reasoned that this low protein regimen should relieve the kidneys of a burden and would tend to aid them in maintaining their functional capacity unimpaired.

In order to demonstrate in a large way the importance of his flew views, Dr. Chittenden secured the cooperation of a group of his colleagues in the faculty of Yale University and a group of volunteers from among the students. These men were allowed a free choice of food, but they conscientiously adhered during the period of the experiment to the regulations which were imposed on the test. A group of soldiers of the United States Army was detailed under the command of a sergeant to participate in the experiment. The diet afforded to these men was similar to that taken by those who volunteered to subsist on a diet low in protein and of a somewhat abstemious character.

In the case of the faculty and student groups the diet chosen contained but little or no meat, and this automatically tended to lower the protein intake to a decidedly low level. In all cases there was free choice of food in these two groups.

There was no indication that the men who participated in this experiment were not in excellent physical condition at the end of the nine months during which they were nourished on an abstemious although somewhat more liberal diet both in energy and protein than that which Dr. Chittenden had himself taken with apparent benefit. The conclusion was drawn that the general standards of food consumption of people were faulty. The faults in the ordinary diet lay in the excessive consumption of food and especially of protein. The view seemed sustained that the body is better nourished when the amount of food metabolized closely corresponds with the minimum which is necessary to cover its requirements. This better nourishment was held to be due to the relief of the digestive organs and the organs concerned with the transformation of protein food, especially the liver, as well as the organs of excretion, the kidneys in particular, from an excessive burden to which the ordinary eating habits of man subject them.

There can be no doubt that the diets which these men took did not lead to any observable deterioration in their physical well-being. All practically maintained their body weights, or at least lost only such amounts as would be anticipated as the result of the physical exercises some of them indulged in during the test. Their strength increased during the experiment where records were taken and all were said by their observers to be in a normal and healthy condition at the end of the experiment.