generating heat and muscular energy (these two being convertible).

The calories used in food tables are kilo-calories, representing the
amount of heat which would raise a kilogramme (1000 grammes) of water 1°
Centigrade. This is the same as raising 1 pound weight 4° Fahrenheit.
According to the table given, 125 grammes of dry proteid are required per
day; this contains 20 grammes of nitrogen and 62 of carbon. When
thoroughly consumed or utilised in the body, the heat or its equivalent in
muscular work equals 512 kilo-calories. Proteids have, of course, an
additional value as tissue formers. The factors used here, of 4.1 and 9.3,
are those commonly employed; but the latest and most reliable research,
taking account only of that part of the food which is actually available
in the body, gives for proteid and carbo-hydrate 4 calories, and for fat
8.9 calories.

Fat has a higher food value than the carbo-hydrates, as 4.1 : 9.3 = 2.27
or 4.0 : 89 = 2.225, according to whether the old or new factors are used.
In the table of analyses 2.225 was used. The standard dietary for a woman,
or of a boy 14 to 16 years of age, is given as equivalent to eight-tenths
that of a man; a child of 10 to 13 six-tenths; of 2 to 5 four-tenths. A
man doing hard work requires one-tenth more. The following table gives
three standard dietaries, and a few actual ones, in grammes per day. The
food of persons in easy circumstances, and of working men in the receipt
of good wages, approximate to the standard dietaries, except that the fat
is higher and the carbo-hydrates proportionately less. This is due to an
abundance of animal food. It was thought unnecessary to give them in
detail:--

Pr't. Fat. C'rb. Cal. N.R.
Hutchison: Man, moderate muscular work 125 50 500 3027 4.9