48 ADVANCED PHYSIOLOGY 



the digestive organs. It is, therefore, useful in regulating 

 digestion, but does not furnish much nutriment. 



Nuts contain fat and in some cases much sugar and pro- 

 teid; Fig. 20. In spite of the fact that they are used 

 extensively by vegetarians, they are, unfortunately, hard to 

 digest. 



Confectionery is a real food and not simply a luxury. It 

 furnishes fuel food only, but this in large amounts. A pound 

 of candy will yield about two-thirds of the fuel needed by 

 the body during a day. 



THE AMOUNT OF FOOD NEEDED 



Even when the body seems to be perfectly quiet it is doing 

 much work. The heart is beating, the blood is circulating, 

 the chest is moving. Much heat is constantly demanded to 

 maintain internal temperature and to counterbalance that 

 given off from the surface. The body, even when quiet in 

 sleep, is giving off heat about as fast as a sixteen- candle 

 power electric lamp; and when awake, but resting, as much 

 as a twenty-candle power lamp. The total amount of enerj 

 expended in various ways by the body may be better appi 

 ciated when it is noted that an ordinary person while remaii 

 ing quiet for a whole day uses up an amount of energy eqi 

 to that required in climbing a mountain five thousa-i 

 feet high. This measurement of energy is usually expre 

 in terms of heat units, called calories. A calorie* is tl 

 amount of heat required to raise the temperature of one kil< 

 gram (about one pint) of water about two degrees F. ; and tl 

 resting body uses from 2000 to 2300 of these units in twenty 

 four hours. If a man rises from his chair, walks about eigl 

 feet and returns, he uses about one unit. When a person 

 working he liberates more heat and expends more energy than 

 when quiet; in order to do this he must oxidize more food. The 

 working man may use two to four times as much food as one 



*This is the large calorie; not the small one, which is only y^ as 

 great; i.e., the amount of heat required to raise the temperature ef 

 sue grai-u of water 1 C. 



