The method may be briefly expressed in two rules.
1. Mastication.—Thorough mastication of all food up to the point of involuntary swallowing, with the attention directed, however, not on the mechanical act of chewing, but on the tasting and enjoyment of the food; liquid foods to be sipped and tasted, not drunk down like water. There should be no artificial holding of food in the mouth beyond the time of natural swallowing, even if, as is to be expected at the start, that swallowing is premature. It is not intended to “count the chews,” or to hold the food forcibly in the front of the mouth, or to allow the tongue muscles to become fatigued by any unnatural effort or position, or in any other way to make eating a bore. On the contrary, every such effort distracts one from the natural enjoyment of food. Pavlov has shown that without such attention and enjoyment of the taste of food, the secretion of gastric juice is lessened. The point of involuntary swallowing is thus a variable point, gradually coming later and later as the practise of thorough mastication proceeds, until the result is reached that the food remains in the mouth without effort and becomes practically tasteless. Thus the food, so to speak, swallows itself, and the person eats without thought either of swallowing or of not swallowing it; swallowing is put into the same category of physiological functions as breathing, which ordinarily is involuntary.
2. Following instinct.—Never to eat when not hungry, even if a meal (or more than one, for that matter) is skipped. And when a meal is taken, not to be guided by the quantity of food offered, or by past habit, or by any theories as to the amount of food needed. The natural taste or appetite is alone consulted, and the subject selects, from the food available, only those kinds and amounts which are actually craved by the appetite. After practise, the appetite gradually becomes more definite and discriminating in its indications.
During the second half of the experiment the two rules above mentioned were continued in force, but a third rule was added, namely, when the appetite was in doubt, to give the benefit of that doubt to low-protein and non-flesh foods. In other words, the influence of suggestion was invoked to hasten the change which had been inaugurated by arousing the natural appetite. Suggestion was introduced merely because the experiment was limited in time. In no case was it allowed to override the dictates of appetite.
Careful records of the amount of food taken and the constituents in (1) protein, (2) fats and (3) starches and sugars, were kept for each man for each day. In order to avoid weighing the food at the table and the annoyance which such a procedure involves, the food was all weighed in the kitchen and served in definite portions of known food value. From the records thus supplied, it was easy, by means of a “mechanical diet indicator” devised for the purpose, to find the proportions of food elements. The first result of the experiment was a reduction in the amount of protein consumed.
During the first four weeks, the men consumed an average of from 2,760 to 3,030 calories per day, of which 120 to 240 were in the flesh foods, such as meats, poultry, fish and shell-fish, and that 2.4 to 2.7 calories of protein were ingested for each pound of body-weight. Translating Professor Chittenden’s figures for the physiological requirement of ingested protein, we find it to be from 1.3 to 1.7 calories per pound of body-weight. Thus the men were at this time consuming nearly double the Chittenden allowance. During the last four weeks of the experiment all these magnitudes were lower. The per capita calories ranged from 2,220 to 2,620, of which only 40 were in flesh foods, and the protein had fallen to 1.4 to 1.9 calories per pound of body-weight, which corresponds closely to the Chittenden standard.
Gymnasium tests were made at the beginning, middle and end of the experiment. These tests were of two kinds—tests of strength and tests of endurance.
During the first period there was a slight increase in strength (from an average “total” strength of 1,076 to 1,118), and during the second period a slight fall to 995, which is about 12 per cent. from the mid-year’s 1,118, and about 8 per cent. from the original 1,076. Thus the strength of the men remained nearly stationary throughout the experiment.
It is fortunate that the strength of the men remained so nearly stationary; for it demonstrates the more clearly that the increase in endurance which will be shown below was an increase in endurance per se, and not in any degree due to an increase in strength. Strength and endurance are entirely distinct and should be separately measured. The strength of a muscle is measured by the utmost force which it can exert once; its endurance by the number of times it can repeat a given exertion well within its strength.
After much consideration and consultation it was decided not to place reliance on the ordinary ergographs as a means of measuring endurance. Instead, seven simple gymnastic tests of physical endurance were employed, and one of mental endurance. The seven physical tests were: