7. Sex influences to a considerable extent the quantity of food consumed, but allowance must be made for totally different habits of life. There are many women who eat as much as men, but the majority require less food, even when doing the same work. Under equal conditions in penal institutions men require about one fifth more solid food than women. Female factory operatives eat from one tenth to one fifth less food than men. Prof. Arthur Goss gives the equivalent that one meal of woman averages 0.8 meal of man at moderate muscular labour.

Mrs. E. H. Richards, as the result of observations (Food as a Factor in Student Life) upon 130 young women students at the University of Chicago, whose average weight was 120 pounds, gives the following table of food consumption in grammes per diem:

Protein.................................................... 120

Fat....................................................... 161

Carbohydrates.............................................. 402

Total...................................................... 659

Potential energy in calories................................... 3,383

Women, on the average, weigh less than men, take less exercise, work less, and live less in the open air, and hence require less food. As a consequence of their habits of life they are more liable to dyspepsia and constipation, which are also factors in reducing the quantity of their food below the standards for men. There are naturally many exceptions to all these general statements.

It is ordinarily impossible or impracticable to definitely weigh the food for individual consumption, but where large numbers of men are being fed by contract in institutions, or as sailors or soldiers, or on exploring expeditions, it becomes necessary to estimate carefully the quantity of food required per diem to maintain normal health and vigour. To facilitate such estimates, tables have been carefully computed based upon the nutrient value of different foods.

Quite exceptionally, persons are observed who subsist in good health upon an abnormally small quantity of food. They usually do but little work, and they are often, but not always, advanced in years. (See Food in Old Age, p. 312).

Fothergill referred to the case of one Wood, a miller of Billericay, who for eighteen years subsisted solely upon a daily allowance of sixteen ounces of flour, which he ate as sea biscuit made into a pudding. By this diet he reduced his figure from extreme corpulency to normal size, and maintained good bodily vigour.

In the preparation of food to be eaten it is customary to allow 10 per cent of waste in calculating the gross quantity for dietaries of institutions, army rations, etc. Mrs. E. H. Richards found that this percentage is somewhat too low.

In computing the quantity of food needed for daily consumption its composition must be taken into account. The estimates of different authors vary somewhat in regard to the necessary quantity of different kinds of food in a mixed diet, but notwithstanding this there is a general correspondence between them. The chief discrepancy concerns the amount of fat to be eaten, and it will be noticed in the following tables that, as a rule, when the fat is cut down the carbohydrate estimate is correspondingly increased.

* According to how the rice is given.