The appearance of black stools is related to diet, drugs and diseases. Dietary causes include eating animal blood products, animal liver, etc.; medication causes include taking bismuth, iron, etc.; and disease causes include acute gastritis, peptic ulcer, cirrhosis of the liver. Steatorrhea is mostly unformed yellow or brown feces with a greasy sheen or foamy surface. 1. Dietary causes: animal blood products and animal liver are rich in iron ions, which can be oxidized in the intestinal tract and form black stools. 2. Drugs: Bismuth, iron and other drugs contain certain metal ions, which can be oxidized in the intestinal tract, resulting in black stools. 3. Disease causes: Acute gastritis has acid reflux, stomach pain and other symptoms; peptic ulcer can have periodic stomach pain (stomach ulcer can have stomach pain after meals, duodenal ulcer can have stomach pain at night or when hungry); cirrhosis of the liver can have jaundice, discomfort in the liver area and other symptoms. For the case of black stool during weight loss, it is recommended to consult the hospital in time to clarify the specific causes and targeted treatment.