346 BIOLOGY FOR BEGINNERS 



The carbohydrates ought always to be more abundant than 

 the fats, because of the much greater amount of energy produced 

 by the latter. This is especially true in warm weather, when the 

 proportion of four times as much carbohydrates will be about the 

 proper diet. 



If the above proportions are followed for all three food stuffs, 

 the ratio for all will be about, 



Proteid, one; fat, one; carbohydrate, four. 



Need of Mixed Diet. We require proteids, fats, and carbohy- 

 drates in about the proportions 1:1:4 but there is no one food 

 that contains these nutrients in these proportions, so it is evident 

 that a mixed diet is necessary. When foods are properly selected, 

 so that the above proportion is obtained, we have what is known 

 as a " balanced ration " and this should be the aim, both of those 

 who prepare and those who eat foods. 



If we use a diet largely of lean meat, we have too high a per cent 

 of proteid. This excess is thrown off by the kidneys and intestines 

 as waste. It overtaxes these organs seriously and is an expensive 

 and unnecessary form of diet. In the same way an excess of fat 

 much above the given proportion, such as would come from a diet 

 rich in fat meats and butter, merely wastes the extra energy or 

 stores it as unnecessary fat tissue in the body. 



A strict vegetarian diet is almost sure to be too rich in carbo- 

 hydrates and has the same result as do fats, fuel is wasted, too 

 little tissue material is provided, and fat tissue may also accumulate 

 from the starches being transformed and stored in this form. 



Remember that, in general, most of the energy should come from 

 carbohydrates and fats, and only enough proteid be taken, to pro- 

 vide for tissue building and repair. If our diet proves to be high 

 in proteid, we are burning tissue foods for fuel, as well as putting 

 extra strain on our system, to remove the nitrogenous waste left 

 by proteid oxidation. 



In general, man has learned to combine foods, to correspond, 

 roughly, to these needs as will appear if we look up the composi- 

 tion of familiar combinations, like the following, 



"Meat and, potatoes," " Bread and butter," " Bread and milk," 



