In view of the evident variations in the amount of food consumed by different persons, even those of the same class, the question is very properly raised whether the measurement of what persons of various classes actually eat gives a proper basis for establishing food standards. It is popularly asserted that most persons eat too much, and that less food would conduce to better health and adequately sustain the fullest activities. This claim is also made by scientists of established reputation, and carefully considered evidence is presented to support it. It must be confessed that the aim of scientific investigation should be to find out what are the real physiological requirements of persons in the several conditions and occupations of life, and it is not safe to assume that the eating habits of those individuals selected for observation are necessarily correct. We know it to be true that many persons have acquired luxurious table habits even to gluttony, and we are sure that much disease and suffering are due to excessive or ill-advised eating. It is not so evident, however, that the great mass of persons in mediocre circumstances and of sober, well-ordered lives could eat much less to the physical advantage of themselves and the race. In discussing this question, facts both of general observation and those derived from scientific inquiry should be considered.

188. The Test Of Experience

In the first place, it must be conceded that in many cases where unrestrained food selection and consumption have prevailed, generation after generation of men and women have grown to a normal, well-developed, and healthy type. We have no reason for supposing that among those people who haye shown a persistence of type and vigor there has not been a free satisfaction of appetite, or, conversely, that there has been either a voluntary or an involuntary limitation of food to a minimum. Moreover, an excess of food over and above real physiological needs must certainly be a physiological burden, and if excessive eating is generally indulged in, we could hardly expect such instances of apparently perfect health and great vigor in persons who freely indulge in a generous diet. It should be admitted that these arguments are of a popular character and are not scientific proof. Let us turn for a moment to arguments of similar nature on the other side.

189. Variable Individual Demands

The advocates of a restricted diet point to the greatly variable food consumption by different individuals of apparently healthy and normal life as good evidence that some must certainly eat more than they need. It has been conceded that there is much overeating, which is the cause of many physical ills. On the other hand unlike eating is not evidence of overeating on the part of some individuals. The activities of the human organism internal and external are very complex and are greatly unlike with different persons without the fact being apparent. One' person sits quietly, walks with the least effort, and uses the minimum effort in performing a given amount of work, while another is of a restless, nervous temperament, is constantly moving, and uses unnecessary exertion in accomplishing a physical task. When we remember that all physical activity of whatever kind is sustained by an exact equivalent of food energy, it is easy to understand why the real food needs of different individuals may vary greatly because of unrecognized differences in muscular activity.