It is easy to compute the chemical equivalents of foods as analysed outside of the body. It is quite another matter to compute them with accuracy within the body. Most writers upon dietetics, however, make some attempt to do this, and the following data may be accepted as approximately correct: One pound of lean beef equals in nutrient value three eggs or two pints of milk. Roast beef contains about the same protein percentage as an egg, but much more fat. One pound of wheat equals 3.5 pounds of potatoes.

Of common cheese, Parkes estimated that "about half a pound contains as much nitrogenous substance as one pound of meat, and one third of a pound as much fat." It requires about 27 pounds of milk to make a pound of butter, and about 10 pounds to make a pound of cheese.

Van Noorden estimates that as a fat former seven grammes of fat equal 9.3 grammes of alcohol.

Oertel says that "one part of fat is iso-dynamic with 2.4 parts of carbohydrates, on an average," and one part of fat develops as much heat and force as 2.11 parts of albumin (Voit).

Church gives the following table of the estimated equivalents of foods which would yield the necessary daily supply of nitrogen if eaten alone:

To obtain the necessary daily supply of carbon: