In the group of hydro-carbons or fats are included all vegetable and animal fatty foods, such as oils, suet, butter, etc.

The value and necessity of fat as an article of food is obvious from the fact that the outer covering of the body beneath the skin is composed of fat. It is fat or adipose tissue which gives the rounded form and curved lines that constitute, according to our ideas, one of the essentials of beauty, and it is moreover this outer covering of fat which protects the body and organs from sudden changes of temperature.

Fat is in constitution a much simpler food principle than the albuminates, and it is shown by analysis to be composed as follows: -