It has been computed that the system needs daily three hundred grains of nitrogen and four thousand eight hundred grains of carbon. To obtain this amount of nitrogen if bread alone were eaten it would require four pounds of bread from the whole wheat. The carbon in this amount of bread largely exceeds that required. If eaten alone, six pounds of beef would be necessary to supply the proper amount of carbon, and twenty-three pounds of eggs. The nitrogen in this amount would far exceed the requirement. One pint of milk, 2-1/2 ounces of bread, and six ounces of beef are about equal in nutritive value. One can see, therefore, why a diet composed of too great a quantity of one substance gives an overbalance of one and an underbalance of another. Therefore, it is more economical to use some fat and sugar in the diet and less meat. More vegetables, perhaps, and more fluid should be taken by many. Authorities vary in their estimates of the amount of food required by the individual. It varies with the activity, the season, the age, the sex, and it varies in the same individual on different days. Billings estimates that the daily diet of a healthy, hard-working man should contain: 20 ounces (1-1/4 pounds) of lean meat; 22 ounces, about 1-1/3 pounds or 1-1/3 loaves of baker’s bread; 10 ounces or about 4 medium sized potatoes; and several glasses of fluid. Since the fluid should be twice the amount of solids, this would mean about 12 glasses. Others compute that the amount of food weighed dry, needed by the average person of sedentary habits, is as follows: For breakfast, 8 ounces; for luncheon, 6 ounces; for dinner, 9 ounces, with 48 ounces or 3 glasses of water. These two give extremes. In active persons from 3 to 3-1/2 ounces (about one-fourth of a pound) of nitrogenous food will replace the nitrogen lost from the body. One ounce (1-1/16 of the ordinary brick) of butter a day supplies the necessary fat, and about 15 to 20 ounces (1 to 1-1/4 pounds) of carbohydrate are required. According to Thompson, from two to three pints of urine are excreted each day; ten ounces of water are lost by the lungs, and eighteen ounces are evaporated from the skin. This amount, about eighty ounces or ten glasses, must be replaced daily to maintain the body in its equilibrium of supply and demand. A part of this is supplied in the food. These figures may be altered somewhat according to the individual or the climate as previously mentioned, but they constitute a fair average. Dr. W. S. Hall estimates that the average man at light work requires, each day 106.8 grams of protein[10] 57.97 grams of fat 398.84 grams of carbohydrates These elements, in proper proportions, may be gained through many food combinations. He gives the following as an example: Bread 1 lb. Lean Meat 1/2 ” Oysters 1/2 ” Cocoa 1 oz. Milk 4 ozs. Sugar 1 oz. Butter 1/2 ”