If it is true that appetite is to be absolutely relied upon in the selection of one’s food, it must enable one to choose the proper food and follow unerringly the best diet for health and efficiency. Many observations lead me to the conclusion that this it fails to do. Environment often so influences the choice of food that individuals, and sometimes whole nations, go astray and fail to follow a diet sufficiently well-balanced to give health or efficiency.
The Chinese have eaten so largely of rice that we find many of them anaemic and weak. Previous to the time when science came to their aid, the Japanese suffered from beri-beri, due to a diet lacking in some protein, vitamine, or mineral. In certain countries there has been a prevalence of corpulence due to the influence of environment on diet. In some sea coast towns the large proportion of fish and small proportions of other desirable articles of food has produced ill-health. You may argue that these results are not due to appetite so much as to environment, poverty, or a failure to follow the real dictates of appetite.
To this I must answer that appetite of itself was not sufficient to indicate what these persons should have eaten, either what they should have gone out and sought in addition to the foodstuffs nearest at hand, or the selections and their proportions which they should have made of the variety which was at hand. Appetite has not impelled men to go out after those foods not offered them in the communities in which they lived. Business enter-prise and chance of profit has been the means of introducing such foods into a country, and appetite has been quick in learning to enjoy such addition to the variety of diet. However, this shows the influence of training and environment on appetite, rather than the surmounting of environment by appetite.
There is no inherent quality in appetite enabling it to indicate when the diet is not well-balanced, or to give an idea of what is missing if it is insufficient. It is true that there may be a kind of yearning or sense that something is wanting when the diet is lacking in essentials, but it has never been sufficient to guide with accuracy and result in perfection in the selection of food.
Furthermore, greater or less degrees of perversion of appetite have been so easily acquired that a considerable proportion of the human race has thereby been led into faulty methods of eating, and often such undesirable foods as they prefer are the only ones which they can be induced to eat. The only argument which will appeal to these people is pain. If they can be convinced that their pain is from a faulty diet, they may be induced to mend their ways; otherwise not. Also in certain diseases, such as ulcer, foods which are harmless for the healthy may cause pain. Appetite never tells these patients what foods will injure them. Some-times pain does. This shows that appetite does not always guide the sick aright.
It has been necessary for science to come to the rescue of appetite and say just what should be eaten. Diet is the most valuable factor in the treatment of diseases of the stomach. It may be interesting to instance some of the cases in which science has shown the way when people had fallen into faulty methods of eating. Science drove beriberi out of the Japanese army. Science gave the remedy for scurvy, which is a disease of faulty diet. Science teaches the amounts and the kinds of foods which should be eaten by the under-nourished to restore health and strength. Science tells us what to avoid when growing too stout.
There are some perversions of appetite which cause cravings for excessive amounts of perfectly good foods, or for seasonings that are undesirable, or even for drugs and poisons. It is a common thing to see people, who at home have acquired a liking for a more or less restricted diet, after going away for several months, learn to eat many new articles and later become very fond of them.
What argument can be advanced against following the light of science in regard to diet, when its value is universally recognized in most fields of endeavor and when it has been proven so definitely that it has pointed the way to an absolute cure of several very serious diseases due to faulty methods of eating? Would it not be wise to search further the field of dietetics for other possible causes of disease, and when found to follow science rather than appetite? Extreme obesity is undoubtedly a disease; dietetic measures, certainly the cure. Mild cases of overweight are undesirable; dietetic measures, the method of relief.