The duration for which patients with acute pancreatitis must fast is determined by the severity of their condition. Some may only need to fast for a day or two, while others may require around three to four days, or even a week. In severe cases of acute pancreatitis, it might be difficult to say how long the fasting could last, potentially around two weeks. Once patients with pancreatitis start eating after a series of active treatments such as anti-infection measures, inhibiting pancreatic secretion, replenishing electrolytes, and balancing acid-base levels, and following treatments like using rhubarb to facilitate bowel movements, if their bowel movements and gas expulsion have mostly returned to normal and amylase levels have largely normalized, they can cautiously start consuming low-fat, high-vitamin, and high-calorie liquid foods.