A gastroenterologist suggests black coffee, when consumed without milk or sugar, offers significant health benefits, including liver fat reduction and protection against long-term liver damage. Dr. Shubham Vatsya recommends a gradual increase in intake, starting with a few sips and potentially reaching 3-4 cups daily for improved liver health and metabolism. He emphasizes that even smaller amounts can be beneficial, suggesting preparation methods like boiling or iced black coffee to maximize its protective qualities for the liver.