The old warning against drinking milk on an empty stomach is not backed by mainstream digestive science. For most healthy adults, milk behaves like any other nutrient mix entering the gastrointestinal tract. Proteins trigger gastric acid secretion, lactose is handled by the enzyme lactase, and fats slow gastric emptying, which can actually prolong satiety.
Discomfort after a glass of milk is usually about individual capacity, not a universal rule. In people with lactose intolerance, undigested lactose passes into the colon, where bacterial fermentation produces gas and draws water by osmotic pressure, leading to bloating or diarrhea. Individuals with gastroesophageal reflux or functional dyspepsia may also feel worse if they add any volume load, including milk, to an already sensitive system.
Health agencies and clinical nutrition guidelines do not single out milk on an empty stomach as uniquely harmful. They emphasize total energy intake, macronutrient balance, and conditions such as lactose malabsorption. The myth persists because a subset of people link their symptoms to timing, while the physiology points more clearly to dose, enzyme activity, and underlying gut sensitivity.
