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