Celsus

The Roman physician Celsus practiced medicine more than 300 years after Hippo-
crates. Celsus identified foods and drugs used to treat common Mediterranean
diseases and wrote that certain categories of food were medically "stronger" than
others, an observation that in the 21st century of the Common Era would be corre-
lated with the concept of caloric density:

All pulses and all bread-stuffs made from grain, form the strongest kind of food; to
the same class belong: [meat from] all domesticated quadruped animals, all large game
such as deer, wild boar, wild ass, all large birds such as crane, goose, and peacock, all
sea monsters, among them which is the whale and such, also honey and cheese. Hence,
it is [obvious why] pastry made of grain, lard, honey, and cheese is very strong food.
Celsus wrote that bread was more nutritious than any other food, that wheat
bread was stronger than millet, and millet bread superior to barley. He wrote that
beans and lentils were stronger than peas, that meat from domesticated animals
provided different strength options to consumers: beef was strongest, pork weakest.
Cuts of meat from larger animals provided "better" nutrition to humans than similar
cuts from smaller livestock. He identified middle-strength foods such as pot-herbs,
edible bulbs and roots, hare, all varieties of edible birds, and all fish except those
that required salting for preservation. Celsus wrote that flightless or "walking birds"
were stronger foods than species that flew; large birds more nourishing than small;
meat from water fowl weaker than meat from birds unable to swim. Celsus suggested
a third category of suitable but weak foods that included stalked vegetables, fruit-
like vegetables (i.e., cucumber), orchard fruits including olives, edible land snails,
and shellfish.
In his dietary system Celsus claimed that young plants and animals provided
less nourishment to humans than older forms of the same species; chickens raised
in coops were superior to those allowed to free-range; grain cultivated on hilly slopes
was more nutritious than grain harvested from valley flatlands; and rock-swimming
fish less nutritious than species swimming over sandy environments. He also wrote
that meat from wild animals was lighter and easier to digest than similar cuts from
domesticated, tamed animals. Celsus observed that fatty meat provided more nutri-
tion to the human body than lean, and that fresh meats were superior to salted,
stewed meats better than roasted.