A diet for philosophers? Seneca, Epistles 2.15.1-2

Seneca does not advocate bodybuilding. His ideal physique is spare, not fleshy with muscle or fat. If someone told him to eat six meals daily for health, he would say that the mind does not do well with constant digestion. Why do we pursue health? What do we want from it? Do our means conform to our ends?

Mos antiquis fuit, usque ad meam servatus aetatem, primis epistulae verbis adicere si vales bene est, ego valeo. Recte nos dicimus si philosopharis, bene est. Valere enim hoc demum est. Sine hoc aeger est animus; corpus quoque, etiam si magnas habet vires, non aliter quam furiosi aut frenetici validum est. Ergo hanc praecipue valetudinem cura, deinde et illam secundam; quae non magno tibi constabit, si volueris bene valere. Stulta est enim, mi Lucili, et minime conveniens litterato viro occupatio exercendi lacertos et dilatandi cervicem ac latera firmandi; cum tibi feliciter sagina cesserit et tori creverint, nec vires umquam opimi bovis nec pondus aequabis. Adice nunc quod maiore corporis sarcina animus eliditur et minus agilis est. Itaque quantum potes circumscribe corpus tuum et animo locum laxa.

The ancient custom, retained up to my day, was to begin each letter saying, "If you are well, I am well." You and I have our own watchword: "If you are practicing philosophy, it is well." In the end, this is enough for health. Without philosophy, the mind is sick, and the body follows suit: even if it has great strength, it is no more effective than if it belonged to someone raving or insane. Therefore, cultivate the health of the mind first, then that of the body, which will not serve you in great stead, if you desire to flourish. It is foolish, friend Lucilius, and quite inconvenient for a literary man, to spend time working the arms, building the neck, and firming up the flanks. However well you feed, whatever muscles you grow, you will never have the strength or weight of a decent bull. Add to this consideration the fact that the overfed mind is broken down, becoming less agile as the body acquires more weight. So, make your body as lean as you can, leaving room for your mind to play.