Not eating for a day can lead to excess stomach acid and damage to the gastric mucosa, which can easily induce gastritis, gastric ulcers, and indigestion. Proper intake of food can neutralize stomach acid and replenish various nutrients needed for the day. Without eating for a day, there will be weakness in the body, dizziness, and lack of memory due to the lack of nutrients. Due to the lack of food present in the stomach, the stomach will be in a state of hunger and the cerebral cortex will alert the gastric glands to secrete a large amount of stomach acid. When too much acid is secreted without the presence of food in the stomach, the gastric acid will cause damage to the gastric mucosa. Once the protective barrier of the gastric mucosa is damaged, the possibility of gastritis and gastric ulcer disease increases. Without eating for a day, the body will feel hungrier, and the intake of food will be higher when ingested, leading to an increased burden on the stomach and intestines, and even causing indigestion.