only a fool asks for more than one extra helping; only fools are gluttons
Proverbial idiomatic expression criticizing greed or lack of restraint, especially when asking for repeated servings. The image is of a fool who keeps asking for more soup (三杯汁) without regard for manners.
There is a proverb that says 'only a fool asks for more than one extra helping.'
He kept asking for seconds again and again, just like the proverb about the fool and the three bowls of soup.
The exact origin is uncertain, but the expression likely comes from a folk saying about a fool who, lacking manners, repeatedly asks for more soup (三杯汁) beyond what is polite.