VIENO SYSTEM OF FOOD MEASUREMENT
The amount of nutrition contained in a given quantity of food is often a determining factor in curative dietetics.
The two most important things to be considered in prescribing foods are:
1 The amount of energy contained in a given quantity
2 The amount of available nitrogen or tissue-building material in a given quantity
ENERGY
Energy is the power to do work. That form of energy with which we are most familiar is mechanical energy, as raising a stone or turning a wheel.
Heat is another form of energy. Heat and work can be converted into each other. The steam-engine turns heat into work, while a "hot box" on a car-wheel is a case of work being turned back into heat.
Amount of heat a food produces determines its energy
Experience shows that a definite amount of heat will yield a definite amount of work, so that the amount of heat produced by a given amount of food, when combined with oxygen, is taken as a measure of its energy. This is ordinarily expressed in calories, a calorie being the amount of heat required to raise the temperature of one thousand grams of water one degree on the centigrade thermometer scale.