Classes of Food Materials._

+--------------------------+----------+----------+----------------+
| Kind of Food. | Protein. | Fat. | Carbohydrates. |
+--------------------------+----------+----------+----------------+
| | | | |
| | % | % | % |
| Meats | 98 | 98 | .. |
| Fish | 96 | 97 | .. |
| Poultry | 96 | 97 | .. |
| Eggs | 97 | 98 | .. |
| Dairy products | 97 | 96 | 98 |
| Total animal food of | | | |
| mixed diet | 97 | 97 | 98 |
| Potatoes | 73 | .. | 98 |
| Beets, carrots, &c. | 72 | .. | 97 |
| Cabbage, lettuce, &c. | .. | .. | 83 |
| Legumes | 78 | 90 | 95 |
| Oatmeal | 78 | 90 | 97 |
| Corn meal | 80 | .. | 99 |
| Wheat meals without bran | 83 | .. | 93 |
| Wheat meals with bran | 75 | .. | 92 |
| White bread | 88 | .. | 98 |
| Entire wheat bread | 82 | .. | 94 |
| Graham bread | 76 | .. | 90 |
| Rice | 76 | .. | 91 |
| Fruits and nuts | 80 | 86 | 96 |
| Sugars and starches | .. | .. | 98 |
| Total vegetable food of | | | |
| mixed diet | 85 | 90 | 97 |
| Total food of mixed diet | 92 | 95 | 97 |
+--------------------------+----------+----------+----------------+

The digestibility of food in the sense of thoroughness of digestion,
however, is of particular importance in the present discussion. Only
that portion of the food that is digested and absorbed is available to
the body for the building of tissue and the production of energy. Not
all the food eaten is thus actually digested; undigest