Fasting gastric pH versus normal gastric pH
The stomach linings generally secrete gastric acid (HCl, KCl and NaCl) and the native pH of the stomach is around 2. The longer you fast, gastric acid levels keep increasing until it reaches around 1-1.5. The food that you eat increases the pH levels of your stomach because the acid reacts with the food while digestion. Depending upon the type of food you eat, the pH levels of your stomach vary, but it is generally around 4-5 (again it varies depending upon the type and amount of food there is in the stomach).