On average it takes about 30 minutes for blood alcohol level to peak after consumption of one drink on an empty stomach, explains the National Institute on Alcohol Abuse and Alcoholism, a council of the National Institutes of Health. Blood alcohol levels approach zero about 2 hours after consumption of that drink. An average 150-pound individual eliminates about 0.5 ounces of ethanol from the body per hour.
However, many factors alter the time course of alcohol metabolism in the body, states NIAAA. Consuming alcohol with food, particularly fatty food, delays absorption of the alcohol into the bloodstream. Therefore, drinking during or after eating prolongs the time between alcohol consumption and total elimination from the body.
The NIAAA also explains that women appear to absorb a greater proportion of consumed alcohol than men do; therefore, after consuming one drink, a woman has absorbed more alcohol than a man. This means a woman takes slightly longer than a man to eliminate each drink from her body.
There are also differences between individuals in the rate of alcohol metabolism, most likely related to genetic factors. The amount of alcohol consumed at one time does not affect the speed at which the alcohol is metabolized, according to NIAAA.