74 



FOOD 



than three fourths water, and meats are fully one half water; 

 even bread, which contains as little water as any food, is about 

 one third water (Fig. 37). But although all foods contain 

 some water, the supply which they yield is too meager to supply 

 bodily needs, and it should be daily supplemented by five or 

 six glasses of good drinking water. 



FIG. 37. Diagram showing the composition of milk, of bread, and of a potato : 

 i, mineral matter ; 2, food ; 3, water. 



How much should we eat. The amount of food we require 

 depends upon how hard we work. The harder we work, the 

 quicker our cells wear out, and the more proteins we need to 

 keep them in repair; the harder we work, the more muscular 

 energy we use up, and the more carbohydrates we need to supply 

 new energy for work. The amount of food we require depends 

 upon the temperature of the place in which we live ; in warm 

 Florida, for example, we require less food than in cold Maine, 

 and in summer we require less food than in winter. The amount 

 of food necessary to keep us active and in good health depends 

 upon what we do and where we live ; a stenographer who works 

 in a well heated room and has no heavy muscular work requires 

 less food than a lumberman who does heavy muscular out-of- 

 door work in a cold climate. By experiment it has been proved 

 that a city clerk needs only about one third as much food as a 



