To consume is to eat or drink: to take food into the body. The word covers the whole act from bite to swallow, and in economics it extends to the purchase and use of goods. Nutrition science studies what populations consume through dietary surveys, linking consumption patterns to health outcomes. Public health guidance aims to shift consumption toward vegetables, whole grains, and water and away from excess sugar, salt, and alcohol. The simplicity of the word belies its importance: every nutritional effect, good or bad, begins with what people actually consume, making accurate measurement of consumption fundamental to the field.