Why Fasting Changes How Medicine Behaves
Fasting is not simply the absence of food. It changes gastric acid levels, slows or speeds gastric emptying depending on the drug, alters the volume of fluid in the gut, and shifts blood glucose and blood pressure in ways that interact directly with what certain medicines are designed to do. A pill that is calibrated for a fed stomach can behave differently when that stomach has been empty for twelve or more hours. The interaction is not hypothetical, it is pharmacological, and it varies by drug class.
