It is not possible in any simple way to estimate the daily fuel need with entire accuracy. The approximate fuel need may be easily estimated, however. To do this, it is necessary to have some understanding of the unit which measures the energy value of foods. Many units of measure are familiar to the average person: the ounce and pound as units of weight, the pint and quart as units of volume, the inch and foot and yard as units of distance, the degree as a unit of temperature. These units are used again and again until the mind remembers the approximate amounts they measure. The same must be true of the unit of measure for the fuel value of foods. It is a basis by which one may compare one food with another and with which one may measure the individual fuel needs.

The unit of measure for the fuel value of foods is the calorie. If a given portion of food has a fuel value of 100 calories and in a day 2,000 calories are needed, one immediately begins to appraise the fuel value of that food. For all practical purposes the following tables are very serviceable in giving an approximate estimate of daily fuel needs.

The average adult person spends about the following amounts of energy under stated conditions:

Asleep................................1/2 calorie an hour for each pound of body weight

Sitting (reading, sewing, knitting)........3/5 calorie an hour for each pound of body weight

Standing..............................3/4 calorie an hour for each pound of body weight Light exercise (dish-washing, cooking for small family, bed-making, sewing by foot power, walking at moderate pace on level road)...............................1 calorie an hour for each pound of body weight Moderate exercise (cooking for large family, sweeping, ironing, scrubbing by hand, work of carpenters, meat carvers, house workers)............................1 1/4 to 1 1/2 calories an hour for each pound of body weight Active exercise (cooking for large groups, ironing and scrubbing with heavy implements, work of farmers, masons, blacksmiths) .............................1 3/4 to 2 calories an hour for each pound of body weight. Severe exercise (heavy muscular exercise, such as that done by lumbermen, excavators, and stevedores)............... 3 or more calories an hour for each pound of body weight

The average child spends about the following amounts of energy: