One should eat only what is sufficient for his well-being

I heard the Messenger of Allah ﷺ saying, "The human being does not fill any vessel that is worse than his stomach. It is sufficient for the son of Adam to eat what will support his back. If this is not possible, then a third for food, a third for drink, and third for his breath."  

سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ: «مَا مَلأَ آدَمِيٌّ وِعَاءً شَرًّا مِنْ بَطْنٍ: بِحَسْبِ ابْنِ آدَمَ أُكُلاَتٌ يُقِمْنَ صُلْبَهُ؛ فَإِنْ كَانَ لاَ مَحَالَةَ، فَثُلُثٌ لِطَعَامِهِ، وَثُلُثٌ لِشَرَابِهِ، وَثُلُثٌ لِنَفَسِهِ۔»