From Sahih Bukhari (Hadith 5397):
Narrated Abu Huraira: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)
Reference: Bukhari 5397