The proteins, of which meat is the principal member, are classified as: Albuminoids: albumin (white of eggs), casein (curd of milk), myosin (the basis of lean meat and gluten of wheat); Gelatinoids: (connective tissue of meat); Extractives: (appetizing and flavoring elements). If protein material is taken into the body in excess of its needs the excess is used as fuel. While vastly more expensive, an excess of protein is worth no more as fuel than starch is; 1 gram of protein produces 4.1 calories of heat, no more than 1 gram of starch. The proteins produce heat and energy when the supply of sugars, starches, and fats is exhausted, but proteins alone form muscle and the larger part of blood and sinew. They are, in this sense, the most important of foods; they are also the most costly. An excess of protein, usually eaten in the daily intake of food, then, is of no practical use and can be eliminated with great benefit to the pocketbook. Meat once a day is sufficient. The excessive consumption of meat can be lessened with no lack of nutrition to the body. The trouble is that meat is the first thing thought of for a meal; it is easily prepared and housewives are not willing to use the thought and effort necessary to secure a balanced meal without it. _CARBONACEOUS FOODSTUFFS_ The carbonaceous foods are those used by the body for heat and energy and are so named because they contain a large proportion of carbon—the heat-producing element. It is the carbon in wood, which, uniting with oxygen, produces heat and light. The carbonaceous foods are all composed of carbon, hydrogen, and oxygen, the difference between them being in the different proportions in which these elements are combined. They are divided into two classes, Carbohydrates and Fats. * * * * * [Sidenote: Carbohydrates] The carbohydrates embrace the _sugars_ and _starches_ and include such substance as the starches of vegetables and grains (notably corn, rice, wheat, and the root vegetables), and the sugar of milk, of fruits, vegetables, and the sap of trees. Their chief office is to create energy. The starches are converted into sugar, so they are together given the one name of carbohydrate. The name means that carbon and hydrogen are contained in them in such a proportion that when oxygen unites with the hydrogen, water is produced and the carbon is liberated. In this chemical process heat is produced. One gram of carbohydrate produces 4.1 calories of heat. They are almost entirely absent from meat and eggs, the animal having converted them into fats.