For the study of so important a problem as the influence of undernutrition upon basal metabolism and vital processes in general, it was essential that the subjects of the research should be men rather than animals, especially as the nation is not so much interested in the better utilization of feeding stuffs for animals as it is in the utilization of food for man. This naturally increased our responsibility and financial obligations, as only those having actual experience with this type of work can realize. Investigators who work entirely with small animals and domestic fowl can have little conception of the perplexities which arise in working with a considerable number of adults.

Observations on one man may be considered in general as typical of observations on men as a whole until striking abnormalities or variations are shown. Thus the ingestion of 100 grams of sugar produces a rise in metabolism with every man. The ingestion of 200 grams of beef likewise produces a rise in metabolism with every man. On the other hand, when the quantitative relationship between the amounts of sugar and beef ingested and the rise in metabolism are to be considered, one may then state properly that experiments on one man are not permissible for a fundamental generalization. It has been the custom of this Laboratory to recognize the legality of this latter contention and a large number of experiments are always made in all our researches. In fact, the Laboratory has even been charged with making too many experiments.1

It is evident, however, that with a problem of such national importance, the study, to be of practical value, must be carried out with a sufficiently large number of men for the results to be reasonably conclusive. As our research on the effect of a reduced diet would probably continue 3 or 4 months, it was necessary to select enough men to allow for all exigencies which might arise, including possible demands for national service. After careful consideration it was decided that the investigation should begin with not less than 12 subjects.

To secure results of general applicability to the civilian population of the United States, an ideal study would include observations not only upon men but likewise upon women and children, but it was believed that if one selected class was followed with great care, it could be reasonably inferred that the general picture obtained would probably in large part apply to other groups. Hence groups of young men were decided on, these to be preferably beyond the age of growth. While in the strictest sense growth persists until 28 years of age, which is shown to be the average age for maximum height, we considered that college students would meet the requirements perfectly.