Two decades ago people who were highly colored and plump, even to excess, were popularly regarded as looking healthy and vigorous. More recently, the general trend of popular opinion has been somewhat away from the earlier point of view, and to-day there is reasonable doubt in the minds of the laity as to whether or not a stout person is as healthy as one of average weight. On the other hand, there is a strong belief that to be thin is a sign of ill health. Such individuals are considered as undernourished or half-starved, less efficient, and less able to withstand either severe work or disease than their better-nourished competitors.

One of the difficulties immediately experienced in attempting to classify individuals as "underweight" or "undernourished" is the fact that even in the language of medical experts the differences are not clearly indicated. Personal conferences with eminent medical examiners and actuaries lead us to the belief that there is no sharp distinction between these two stages. Individuals who are underweight would have been, a decade ago, classified as undernourished, but with the increasing belief that underweight is not necessarily disadvantageous to health, medical examiners are rather disinclined at the present time to consider mere underweight as an index of undernourishment unless supported by other evidence. Still, it is the popular belief that the best efficiency is obtained from men who are well nourished rather than from those who are underweight; thus the distinction between "undernourished" and "underweight" is not readily made.

It is likewise difficult to state quantitatively what is meant by a fat, medium fat, thin, or moderately thin person. The best practice at the present time uses the average weight of individuals for a given height, age, and sex, and ordinarily indicates differences of 5,10, or 15 pounds over or under weight, without statement as to whether or not the persons are undernourished. It is quite clear, also, that the general build of the body must be taken into consideration, for if an individual is tall and extremely thin he might be classified as undernourished, particularly if the frame is very broad. Still, in the absence of a more exact classification, it is sufficiently satisfactory to use the average weight and indicate, in accordance with the best actuarial usage, whether the person is over or under weight in terms of plus or minus 5 or multiples of 5 pounds.