duce 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
proportion as nature supplies them, are necessary and important food
elements.

The nitrogenous food elements especially nourish the brain, nerves,
muscles, and all the more highly vitalized and active tissues of the
body, and also serve as a stimulus to tissue change. Hence it may be
said that a food deficient in these elements is a particularly poor
food.

The inorganic elements, chief of which are the phosphates, in the
carbonates of potash, soda, and lime, aid in furnishing the requisite
building material for bones and nerves.

PROPER COMBINATIONS OF FOODS.--While it is important that our food
should contain some of all the various food elements, experiments upon
both animals and human beings show it is necessary that these elements,
especially the nitrogenous and carbonaceous, be used in certain definite
proportions, as the system is only able to appropriate a certain amount
of each; and all excess, especially of nitrogenous elements, is not only
useless, but even injurious, since to rid the system of the surplus
imposes an additional task upon the digestive and excretory organs. The
relative proportion of these elements necessary to constitute a food
which perfectly meets the requirements of the system, is six of
carbonaceous to one of nitrogenous. Scientists have devoted much careful
study and experimentation to the determination of the quantities of each
of the food elements required for the daily nourishment of individuals
under the varying conditions of life, and it has come to be commonly
accepted that of the nitrogenous material which should constitute one
sixth of the nutrients taken, about _three ounces_ is all that can be
made use of in twenty-four hours, by a healthy adult of average weight