Eat at 3 pm. Black coffee jelly bar, also called prebiotic enzyme jelly, contains digestive enzymes, which can improve constipation and digestion. It is a kind of food that can hydrolyze fat, protein and sugar in the digestive tract, thus helping the intestinal tract to accelerate digestion and absorption. It is best to eat at 3 pm every day, which can digest fat during the day and reduce the absorption of fat at night.