No laws of physiology are more commonly disregarded than those upon which the statements and advice given in this section are based. The first of these laws, concerning the necessary time between meals, is a matter of common knowledge to every physician making X-ray examinations, or even casually acquainted with them. In a normal individual, four and a half or five hours are required for the stomach to empty completely after each meal. Food put into the stomach before it has entirely emptied from the previous meal causes that meal to be held in the stomach, often several hours longer than it should be.
This allows the mixed and partially digested food to undergo decomposition, fermentation, and even putrefaction. The delicate structures and mechanisms of the stomach and other organs are injured. The glandular secretions are altered, and in time the muscle tone of the stomach is impaired. Abnormal chemical products of this decomposition disorder the nerve mechanism, the blood vessel action, and many other functions. Headache, sour stomach, morning-after depression, excess or deficiency of hydrochloric acid, and impairment of digestive activity often result. These are only a few of the direct results. Many other indirect effects, of a disturbing and disease-producing nature, occur.
Late Suppers.—The popular custom of evening dinners and banquets, and very late suppers, impairs the appetite for breakfast, and makes people believe that the no-breakfast plan is better for them. But "this is reversing the natural order."—"Counsels on Diet and Foods," p. MI. The truly physiologic requirement is for a susbtantial breakfast; a larger midday dinner, mostly of vegetables; and a light supper. For sedentary workers, two meals a day, or two meals and a light supper, is best. With the addition of physical labor, "the objection to the third meal is to a great extent removed."—Id., p. 178. The reason for this, as we know it, is not that physical labor requires more protein food, but more fuel food; that is, more calories, which should come largely from the natural unrefined carbohydrates of vegetables, fruits, milk, and whole-grain breads and cereals.
Eating Between Meals.—Few realize the great amount of harm which comes from nibbling at confections, peanuts, ice cream, sandwiches, or other food, between meals. People are often advised to take milk between meals as a means of improving nutrition, but even this is not advisable. In the Berkeley, California, schools one group of children was given a glass of milk between meals, and another group a glass of orange juice. It was found that those having the fruit juice did much better and had a keener appetite for their regular meals, than those who were given the milk between meals.
The reason is plain. Fruit juices require no stomach digestion, and pass on into the intestine almost immediately. On the contrary, milk must be curdled by the rennin of the gastric juice, and becomes a solid food which requires stomach digestion the same as cheese. Fruit juices can usually be better taken before or between meals, so as not to lessen stomach capacity for the meal itself. Instead of interfering with the appetite for the regular meal, they improve it.
X-Ray Evidence.—By means of X-ray examinations of the stomach, it is possible to determine just how long the emptying time of the stomach is delayed by food taken between meals. The outlines below are from two groups of such experiments. In the first (see Life and Health, April, 1924), a breakfast of cereal and cream, bread and butter, cooked fruit, and an egg was given. The stomach was empty or nearly so in four hours. On other days this same meal was repeated, but with various other foods eaten two hours later. The results in prolonging the stay of the food in the stomach are given below for each day of the test:
Effect on Breakfast Left in Stomach
A residue remained at 6 hours.
A large residue at 9 hours.
A residue at 9 hours.
A residue at 8 hours.
In another series of experiments in which an ordinary normal breakfast was eaten, the stomach was completely empty in four and one half hours. On another day after breakfast, every hour and a half, a slice of bread and butter was eaten, but no dinner was taken. Half of the breakfast remained in the stomach after nine hours. No further X-ray examinations were made; so complete emptying time was not known. (See Life and Health, September, 1931.)
After a breakfast of the same foods, every hour and a half a five-cent bar of Hershey's milk chocolate was taken. Half of the breakfast remained in the stomach after nine hours.
Again, breakfast was eaten at eight, dinner at noon, and supper at five-thirty. Twice in the forenoon and twice in the afternoon, chocolate candy was eaten. At nine-thirty that night, more than half of the breakfast was still in the stomach—thirteen and one-half hours after breakfast was taken.
In one case, a ten-cent bag of peanuts was carried in the pocket, and a few eaten at irregular intervals. Eleven hours later, a large amount of the breakfast was still in the stomach. In another individual whose stomach was ordinarily empty six hours after breakfast, a slice of bread and butter was taken halfway between breakfast and dinner. A small amount of the breakfast remained in the stomach eight hours after it was eaten.
Mrs. White says: "If all would eat at regular periods, not tasting anything between meals, they would be ready for their meals, and would find a pleasure in eating that would repay them for their effort."—Id., p. 179. Besides enjoying a keen appetite and a relish for food, many distresses and even serious disabilities would be avoided if all would practice strict regularity in eating their meals
* Parallel scientific discussion to be read in connection with section IX, "Regularity in Eating," in the book, "Counsels on Diet and Foods."