When a person drinks alcohol, the alcohol is absorbed from the stomach and small intestine into the bloodstream. The amount of alcohol in the blood is called blood alcohol concentration (BAC). As blood travels to the brain, the alcohol in the blood produces the signs and symptoms of inebriation, or drunkenness. BAC is expressed as the weight of alcohol in a fixed volume of blood, for example, grams per liter.

In addition to how much a person drinks, several factors affect the amount of alcohol in the blood. Eating along with drinking alcohol decreases the amount of alcohol that can be quickly absorbed into the blood. Having more than one drink in an hour causes the BAC to increase rapidly. The percentage of body fat in a person's total weight also affects BAC. More fat means less body water into which the alcohol can...