At light muscular exercise (dressing, standing, walking, etc.), 6 × 1.0 Calories = 6.0 Calories per pound.
At active muscular exercise 2 hours, 2 × 2.0 Calories = 4 Calories per pound.
Total Calories per pound for 24 hours, 18; 18 × 154 pounds (the weight of the average man) = 2772, or approximately 2680, Calories per day required. Calculate in this way the energy requirement for various grown persons whom you know.
Energy requirements during growth.—In estimating food requirements of those who are under twenty-five years old, we must bear in mind that the same materials which serve for fuel serve in part for building material. Protein is used for muscle building as well as for supplying energy, and the larger one grows, the greater the reserves of carbohydrate and fat which he can carry. Furthermore, internal activity is greater in the young than the middle aged or very old, and external activity is apt also to be greater. Think, for instance, how much running children do compared with their parents. For all these reasons, we cannot use the table for adults in calculating the energy requirement of young people. In the following table an attempt has been made to take account of their greater needs, but the estimates include only moderate exercise; with hard work more will be required. Notice that the highest allowance per pound of body weight is for the youngest children.
Energy Requirements during Growth
| Age in Years | Calories per pound per day |
| Under 1 | 45 |
| 1-2 | 45-40 |
| 2-5 | 40-36 |
| 6-9 | 36-30 |
| 10-13 | 30-27 |
| 14-17 | 27-20 |
| 17-25 | not less than 18 |
With these two tables for calculating energy requirement we can determine about how much will be needed by each member of the family. A group consisting of a professional man, his wife, and three children under 16 will require about 10,000 Calories per day; a workingman’s family with the same number of children from 12,000 to 14,000, because of the harder work which both parents and possibly the children will do.
Protein requirement.—Since few of our foods consist of a single foodstuff, and we are not likely to make even a single meal on pure fat, or pure protein, or pure carbohydrate alone, we are sure to get some building material in any diet, but we must see to it that we are getting amounts which furnish the best possible conditions for growth and repair.
As we have already seen, nitrogen in the form of protein is necessary to the life of every cell in the body. From protein, too, muscle is built, though we cannot build good muscle merely by feeding protein; a diet moderate in its amount of protein, but with plenty of fuel for healthy exercise is best for muscle building. Under all ordinary conditions, if ten to fifteen Calories in every hundred (10 to 15 per cent of the total Calories) are from protein, the need for this kind of building material will be met. Thus a family requiring 10,000 Calories per day should have from 1000 to 1500 of these as protein Calories. The following table gives the protein