PROPER AMOUNTS OF FOOD 



327 



ct locomotive 

 uses on)/ \Q% 

 of the bound up 

 energy- in Cool 



Cocci 



an automobile 

 uses 20% of 

 t"he bound up 

 energy in fuel 



ctn2an,cctn. 

 use 33% of 

 the energy 

 in "his -food 



"potatoes^ 



Man is evidently an efficient machine as com- 

 pared with a locomotive or automobile. 



in the fuel is released by oxidation in the fire box, as it is 

 when gasoline is exploded in the cylinders of the automo- 

 bile. In the body the principle involved is the same, foods 

 are oxidized and energy 

 is released. But this is 

 done in the body cells, 

 the oxygen which re- 

 leases the energy being 

 taken in when we 

 breathe. 



The Energy Values 

 of Food Can Be Meas- 

 ured. It has taken a 

 good many men and a 

 large number of experi- 

 ments to prove that different foods have different fuel 

 values. Just as in measuring distance we use the inch or 

 the foot as a unit of length, so we use a unit of heat called 

 the Calorie. This is roughly the amount of heat needed 

 to raise the temperature of one pound of water 4 degrees 

 Fahrenheit. Thus it became possible to estimate exactly 

 how many units of heat were locked up in given amounts 

 of different kinds of foods. It has been found that a 

 given weight of fat will furnish about twice as many 

 Calories as the same weight of carbohydrates or proteins. 



Should We Count Our Calories? After knowing the 

 number of Calories in different foods, the next step was 

 for scientists to find out the Calorie requirements of the 

 human machine. As you can see, these requirements would 

 not always be the same. Any one who does hard work 

 requires more energy-producing foods in a given time 

 than when he is sitting quietly at home. An adult resting 

 quietly in bed needs only from 1500 to 1800 Calories a day, 

 depending on his weight, while the same man, doing hard 

 muscular work, would need at least 4000 Calories a day- 



