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 اللهِ ﷺ يَقُولُ: «مَا مَلَأَ ابْنُ آدَمَ وِعَاءً شَرًّا مِنْ بَطْنٍ: حَسْبُ ابْنِ آدَمَ أُكُلَاتٌ يُقِمْنَ صُلْبَهُ؛ فَإِنْ كَانَ لَا مَحَالَةَ فَثُلُثُ طَعَامٍ، وَثُلُثُ شَرَابٍ، وَثُلُثٌ لِنَفْسِهِ۔»