Lycurgus (17.4-17.5)

But the boy who is caught gets a flogging and must go hungry. For the meals allowed them are scanty, in order that they may take into their own hands the fight against hunger, and so be forced into boldness and cunning. This is the main object of their spare diet; a secondary one is to make them grow tall. For it contributes to height of stature when the vitality is not impeded and hindered by a mass of nourishment which forces it into thickness and width, but ascends of its own lightness, and when the body grows freely and easily.

The same tiling seems also to conduce to beauty of form; for lean and meagre habits yield more readily to the force of articulation, whereas the gross and over-fed are so heavy as to resist it. Just so, we may be sure, women who take physic while they are pregnant, bear children which are lean, it may be, but well-shaped and fine, because the lightness of the parent matter makes it more susceptible to moulding. However, the reason for this I must leave for others to investigate.