Messenger of Allah ﷺ said, "A believer eats in one intestine (is satisfied with a little food), and a kafir (unbeliever) or a hypocrite eats in seven intestines (eats too much).  

قَالَ رَسُولُ اللَّهِ ﷺ إِنَّ الْمُؤْمِنَ يَأْكُلُ فِي مِعًى وَاحِدٍ وَإِنَّ الْكَافِرَ أَوِ الْمُنَافِقَ فَلاَ أَدْرِي أَيَّهُمَا قَالَ عُبَيْدُ اللَّهِ يَأْكُلُ فِي سَبْعَةِ أَمْعَاءٍ وَقَالَ ابْنُ بُكَيْرٍ حَدَّثَنَا مَالِكٌ عَنْ نَافِعٍ عَنِ ابْنِ عُمَرَ عَنِ النَّبِيِّ ﷺ بِمِثْلِهِ  

A man used to eat much, but when he embraced Islam, he started eating less. That was mentioned to the Prophet ﷺ who then said, "A believer eats in one intestine (is satisfied with a little food) and a Kafir eats in seven intestines (eats much). "  

أَنَّ رَجُلاً كَانَ يَأْكُلُ أَكْلاً كَثِيرًا فَأَسْلَمَ فَكَانَ يَأْكُلُ أَكْلاً قَلِيلاً فَذُكِرَ ذَلِكَ لِلنَّبِيِّ ﷺ فَقَالَ إِنَّ الْمُؤْمِنَ يَأْكُلُ فِي مِعًى وَاحِدٍ وَالْكَافِرَ يَأْكُلُ فِي سَبْعَةِ أَمْعَاءٍ