760 Reading-Course for Farmers". Wives. 



in a pound, of 1259 calories per pound. The calorie value of foodstuffs, 

 protein, carbohydrate and fat, is determined in the same way. One 

 measure of the food value of various foods is the number of calories 

 they can yield. It has been found that i gram of protein yields to the 

 body about 4 calories, i gram of carbohydrate 4 calories, and i gram 

 of fat 9 calories. In other words, weight for weight fat has a much 

 higher fuel value than either of the other foodstuffs. The amount of 

 energy spent by the body each day is also measured in terms of the heat 

 unit or calorie. If we learn that in the day's efforts 2500 calories of 

 energy have been spent and we know how many calories each of the 

 foodstuffs will yield, it is a simple matter theoretically to determine 

 the total amount of food which will cover the expenditure. 



Daily food requirement. — Before we attempt any solution of the prob- 

 lem of the amount of man's daily food supply, we must know something 

 of the conditions which govern it. A certain amount of food is always 

 necessary to keep the machinery going. Even if we do not work we 

 must still eat a rather considerable amount of food. Beyond this, the 

 factor having the most important influence on the daily food need is 

 the activity of the body. If the muscle cells which make up the bulk 

 of the soft tissues are made to work hard, as in exercise and manual 

 labor, the need for food is greatly increased. For example, the man 

 who works in the lumber camps, using his muscles in the hardest kind 

 of way, may require two or three or even four times as much total food 

 as the man who sits still at a desk and writes all day. Most of the body 

 cells of the hard worker are exceedingly active, and he uses not only 

 more material but such as might prove harmful to the less active in- 

 dividual. Age has a considerable influence on the relative amount of 

 food consumed. The body cells of a child are much more active than 

 those of the grown person, and the child eats more food in proportion 

 though not in total amount. In respect to activity the child resembles 

 the lumberman, but the delicacy of the child's immature body makes 

 the choice of food materials exceedingly important, for in this case there 

 must be nothing to overtax cells which have not attained full-grown 

 powers. Build , sex, climate, season, and individuality all influence to 

 some extent the amount of food needed, but these are minor factors. 

 The short, fat man requires less food than the tall, thin man of the same 

 weight, for fatty tissue is sluggish, and the thin man has also a larger 

 surface exposure. Women are said to require less food than men, but 

 this difference is more apparent than real. Men and women of the same 

 size and activity have a similar food requirement. There seems to be 

 no real sex differences excej^ as to size and work. In warm climates 



