Beef juice is often used as a source of iron for children and undoubtedly it is one which is palatable and digestible, but it takes a quarter of a pound of beef to get a few tablespoonfuls of juice, and a tablespoonful of juice would hardly contain as much iron as one egg yolk; and it seems probable that the iron of the egg yolk would be better utilized for the making of good red blood.
Meat is good fuel for the human machine if used in moderate amounts along with other food.

But meat is no better fuel than other food.

An ordinary lamb chop will furnish no more calories than a dish of oatmeal, a piece of bread an inch thick and three inches square, a large apple or banana, an egg, five ounces (five-eighths of a cup) of milk, or a tablespoonful of peanut butter.

The fatter meat is the higher its fuel value (providing the fat is used for food).

A tablespoonful of bacon fat or beef drippings has the same fuel value as a tablespoonful of butter or lard, or as the lamb chop mentioned above.