Food-quantity was the first consideration of Diet-Science when it began the study of Human Nutrition. The food-amounts sanctioned as dietary standards have been greatly modified of late, due to more comprehensive experimentation and searching investigation.

The variation in food-habits, as shown by investigation-records, and in nutritive possibilities, as tested by experiment, is very wide. Yet there are diet-limits that it is not physiologically advisable to overstep, if indeed safe. These are flexible, because they change with climate, occupation, diet-habit, size, sex, age, health. Diet-standards have value as a basis for selecting the dietary. For Food-Variety, see p. 224.

Food-Amounts according to Age, p. 182; Old-Age Requirement, p. 211; Food-Need of Childhood, pp. 203-205; Food-Utilization and Digestibility of Foods, pp. 218-219.

Metabolism (the process of actively breaking down and building up body-tissue) is increased in childhood and decreased in age. The protein-need changes during growth and old age, but not with work.

Occupational Energy-Requirement

(From Report of Journal of the A merican Medical Association on Respiration Experiments of Physiological Institute at University of Helsingfors, in Finland. The carbon-dioxid output of these persons was scientifically determined during rest and during work. With this as a basis the energy needed to live and to work for 8 hours a day was calculated).

Calculation Of Dietaries. Selection Of Dietary

Choose foods preferred by those to be fed. Introduce new foods periodically; discontinue if digestion is disturbed.

Note especially protein-foods that seem digestible. Use these. Combine with "incomplete" proteins some "complete," p. 219.

Consider digestibility (p. 218) of all foods used; also ease of digestion.

Use together foods of rapid and slow utilization, as sugar and starch.

Combine Building - Energy - Digestion Foods, pp. 172-174.

Acid-excess is undesirable in the body. To prevent this, use base-producers (potatoes, apples, raisins, cantaloupes) with acid-producers (meats, cereals, prunes).

Approximate the general menus on pp. 194-195. Use foods in season. Prepare food freshly.

It is not advisable to attempt to calculate the amount of food as it is used daily. The sources of error are so many that the total inaccuracy exceeds that of a larger more general calculation, such as is suggested.

Calculation Of Dietary

To estimate food-quantity for a family: Record all staple foods on hand at the beginning and end of a week. Add to the difference the foods purchased during the week, if used.

Subtract 10% (waste in raw material and through preparation). Divide remainder by number of those fed (using proportions on p. 182).

This gives food-bulk consumed per capita per week. For succeeding week adjust to standard if not in accord.

Note weights of each food used. Calculate P - F - CH in amount of each used. (Food-Tables, pp. 190-193.) Add these for all foods eaten.

Compare proportions of these totals with standard. If necessary, change foods to secure similar relation. This gives standard diet-balance of food-constituents.

Multiply total P + CH (in oz.) by 125 and F by 250. The sum of these is a close approximation of the calories of the food eaten.

This may be obtained by adding calories given in Food-Tables, but to do so makes the calculation more cumbersome. This gives the Fuel Value or Heat-Energy of the dietary. Distribution by proportions (p. 182) gives calories per person. Estimate cost of the adjusted dietary per family per year. Compare with Income-Distribution, p. 183. Food-Cost, p. 156. This gives food-expense as economic factor of income.