The requirements of the system differ greatly, according to the degree of
heat, the purity of the air, and the degree of physical exercise. What
suffices at the equator would be but a morsel at the pole. What sustains
the quiet student would starve the active athlete.
When Volney spoke in surprise of the few ounces required to sustain the
Bedouin, he forgot the purity of the air of the desert, as well as the
indolent life of the Arab.
When we offer as example the frugal diet of Cornaro, which was twelve
ounces of solid food, with fourteen ounces of wine, daily, we must
remember that the celebrated man lived a life of moderation, avoided bad
air, and guarded against the extremes of heat and cold.
The data of Frerichs, the observations of Sir John Sinclair, and the
determinations of Professor Horsford, show that eighteen ounces of
properly selected food may sustain life; and they also show that the
nutrient substances must be of known value.