I 



DAILY FUEL NEEDS 133 



are known collectively as the meiabol'ic processes (Gr. metaholos, 

 changeable). These changes release heat as a by-product and 

 this heat can be measured in calories. The heat-producing activ- 

 ity of the body protoplasm during sleep or rest represents the en- 

 ergy which is essential for carrying on the vital processes and 

 is known as basal metab'olism. It is represented in a man of 

 average weight (about 150 pounds) by about 65 calories an hour. 

 Normal Heat Output. — The following table gives the result of 

 some experiments made to determine the hourly and daily expen- 

 diture of energy of the average normal grown person when asleep 

 and awake, at work or at rest : — 



AvEEAGE Normal Output of Heat from the Body 



Conditions of Muscular Activity 



Average 

 Calories 

 PER Hour 



Man at rest, sleeping (basal metabolism) . , 



Man at rest, awake, sitting up 



Man at light muscular exercise 



Man at moderately active muscular exercise 



Man at severe muscular exercise 



Man at very severe muscular exercise . . . 



65 calories 

 100 calories 

 170 calories 

 290 calories 

 450 calories 

 600 calories 



It is very simple to use such a table in calculating the number 

 of calories which are spent in twenty-four hours under different 

 bodily conditions. For example, suppose the case of a clerk or 

 school teacher leading a relatively inactive life, who 



sleeps for 9 hours X 65 calories = 585 



works at desk 9 hours X 100 calories = 900 



reads, writes, or studies 4 hours . . X 100 calories = 400 

 walks or does light exercise 2 hours . X 170 calories = 340 



2225 



This comes out, as we see, very close to example 6 of the table 

 on page 134.^ 



, Daily Fuel Needs of the Body. — It has been pointed out that 

 the daily diet should differ widely according to age, occupation, 



^ The foregoing tables have been taken from the excellent pamphlet of the Cornell 

 Reading Course, No. 6, Human Nutrition. 



H. NEW CIV. BIOL. — 10 



