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Asterix in Olympia

... if ten pounds are too much for a particular person to eat and two too little, it does not follow that the trainer will order six pounds; for this also is perhaps too much for the person who is to take it, or too little—too little for Milo, too much for the beginner in athletic exercises. Aristotle Nicomachean Ethics, Book II.6

It is an admitted principle that gymnastic exercises should be employed in education, and that for children they should be of a lighter kind, avoiding severe diet or painful toil, lest the growth of the body be impaired. The evil of excessive training in early years is strikingly proved by the example of the Olympic victors; for not more than two or three of them have gained a prize both as boys and as men; their early training and severe gymnastic exercises exhausted their constitutions. When boyhood is over, three years should be spent in other studies; the period of life which follows may then be devoted to exercise and strict diet. Men ought not to labor at the same time with their minds and with their bodies; for the two kinds of labor are opposed to one another; the labor of the body impedes the mind, and the labor of the mind the body.
Aristotle, Politics, Bk. 8, 1338b–1339a

Great attention was paid to the training of the athletae. They were generally trained in the palaestrae, which, in the Grecian states, were distinct places from the gymnasia, though they have been frequently confounded by modern writers. [ PALAESTRA.] Their exercises were superintended by the gymnasiarch, and their diet was regulated by the aliptes According to Pausanias, the athletae did not anciently eat meat, but principally lived upon fresh cheese (turon ektwn talarwn); and Diogenes Laërtius informs us that their original diet consisted of dried figs, moist or new cheese (turoi), and wheat (puroi). The eating of meat by the athletae is said, according to some writers (Paus.), to have been first introduced by Dromeus of Stymphalus, in Arcadia; and, according to to others, by the philosopher Pythagoras, or by an aliptes of that name (Diog. Laërt.). According to Galen (De Val. Tuend.), the athletae, who practised the severe exercises barei, ate pork and a particular kind of bread; and from a remark of Diogenes the Cynic (Diog. Laërt. ), it would appear that in his time beef and pork formed the ordinary diet of the athletae. Beef is also mentioned by Plato (De Rep. ) as the food of the athletae; and a writer quoted by Athenaeus (ix. p402c-d) relates that a Theban who lived upon goats' flesh became so strong, that he was enabled to overcome all the athletae of his time. At the end of the exercises of each day, the athletae were obliged to take a certain quantity of food, which was usually called anagkofagia and anagkotrofia, or biaioj trofhj (Arist. Pol. ); after which, they were accustomed to sleep for a long while. The quantity of animal food which some celebrated athletae, such as Milo, Theagenes, and Astydamas, are said to have eaten, appears to us quite incredible . The food which they ate was usually dry, and is called by Juvenal coliphia. William Smith, A Dictionary of Greek and Roman Antiquities, John Murray, London, 1875.