cannot be converted into blood in tissue, serve an important purpose by
giving bulk to the food.

With the exception of gluten, none of the food elements, when used
alone, are capable of supporting life. A true food substance contains
some of all the food elements, the amount of each varying in different
foods.

USES OF THE FOOD ELEMENTS.--Concerning the purpose which these
different elements serve, it has been demonstrated by the experiments of
eminent physiologists that the carbonaceous elements, which in general
comprise the greater bulk of the food, serve three purposes in the body;

1. They furnish material for the production of heat;

2. They are a source of force when taken in connection with other food
elements;

3. They replenish the fatty tissues of the body. Of the carbonaceous
elements,--starch, sugar, and fats,--fats produce the greatest amount of
heat in proportion to quantity; that is, more heat is developed from a
pound of fat than from an equal weight of sugar or starch; but this
apparent advantage is more than counterbalanced by the fact that fats
are much more difficult of digestion than are the other carbonaceous
elements, and if relied upon to furnish adequate material for bodily
heat, would be productive of much mischief in overtaxing and producing
disease of the digestive organs. The fact that nature has made a much
more ample provision of starch and sugars than of fats in man's natural
diet, would seem to indicate that they were intended to be the chief
source of carbonaceous food; nevertheless, fats, when taken in such