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When you drink alcohol, you start to feel its effects quickly. Ethanol, its intoxicating component, enters your bloodstream and circulates through your body, affecting many organs and functions. However, your body starts working immediately to “metabolize” ethanol molecules. It filters them out of the bloodstream and breaks them down into smaller molecules that can be used, stored, or eliminated.
Once this happens, the inebriating effects disappear. So, how fast is alcohol metabolized? And how long will it take for you to be legal to drive after drinking?
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What Is Alcohol Metabolism?
Ethanol is a water-soluble molecule that passes easily into your bloodstream as it travels through your digestive system. Most of it is absorbed in the upper intestinal tract, or small intestine, after it leaves the stomach. However, some is immediately metabolized in the stomach, and some travels all the way to the colon before absorption.
Once the blood makes its way to the liver, hepatocyte cells in that organ attack the ethanol molecules with a combination of enzymes. The first, alcohol dehydrogenase (ADH), converts ethanol to acetaldehyde, a toxin. The second, acetaldehyde dehydrogenase (ALDH), breaks it down further into acetate, a short-chain fatty acid. Acetate increases blood flow into the liver, depresses the central nervous system, and affects various metabolic processes before being mostly converted to carbon dioxide.
Most alcohol metabolism occurs in the liver through this enzymatic process. However, other cells in the stomach and digestive system use different metabolic processes to break down ethanol. Because many factors contribute to alcohol metabolism, answering the question, How fast is alcohol metabolized? differs significantly from person to person. Everyone has a unique combination of bacteria, enzymes, and other chemicals in their blood due to their genes, diet, medical history, and environment.
Does The Type Of Drink Affect How Fast Alcohol Is Metabolized?
Technically, no. Alcohol is metabolized at the same rate regardless of whether it comes from beer, wine, or hard liquor. However, a drinker’s perception of “one unit” of alcohol can be skewed by the type of drink. Further, there is no worldwide standard of what constitutes a “unit.”
The World Cancer Research Fund (WCRF) considers 10-15 g of ethanol as one “standard” drink, advising men not to exceed two per day and women only one. In the United Kingdom, a standard unit is 8 g of alcohol; in the U.S., one ‘standard’ drink contains 14 g of pure alcohol.
Using the U.S. measurement, one unit equals:
- One can (12 oz.) of 5 percent ABV beer
- One 5 oz. glass of 12 percent wine
- 1.5 oz. shot of 80 proof (40 percent) alcohol
It’s easy to see how a drinker may not realize that one can of beer and a typical neat pour of straight bourbon have an equivalent amount of ethanol.
Is There Any Way To Estimate How Fast Alcohol Is Metabolized?
Studies generally show that the amount of pure alcohol an “average” person weighing about 150 pounds can metabolize per hour is about 7 g (about half of a U.S. “standard” drink). However, rates vary significantly based on numerous factors.
Frequency Of Alcohol Use
In heavy drinkers, the average metabolic rate can be significantly faster than occasional drinkers. However, alcoholism damages the liver over time. As this damage becomes more severe, the ability to metabolize alcohol decreases significantly.
Fat absorbs less alcohol from the blood than muscle. Individuals with higher muscle-to-fat ratios will have less alcohol in their bloodstream than those with more fat. In any two people of equal weight, the one with more body fat will usually have a higher BAC reading after they consume equivalent amounts of alcohol.
Independent of body composition, there are other biological differences between how fast alcohol is metabolized in women and men. Studies show that women’s livers metabolize alcohol more quickly than men’s. However, men may have the advantage when it comes to first-pass metabolism: More of the alcohol is metabolized by their stomach before it ever enters the bloodstream. As a result of this discrepancy, women experience a higher blood alcohol content (BAC) than men of similar weight and body composition after drinking the same amount of alcohol.
Eating before drinking speeds up the alcohol metabolic process significantly. It also delays the absorption of alcohol into the bloodstream and allows more time for first-pass metabolism. As a result, BAC rises more slowly if there is food in your stomach.
Can Your BAC Rise After You Have Stopped Drinking?
Yes! Especially if you have had a relatively modest amount of alcohol on a full stomach, it can take a while to enter your bloodstream. It will spend some time being churned up with your stomach contents before making its way into your intestines, where most ethanol absorption occurs. As digestion proceeds, your BAC will rise; when all the ethanol has been extracted, your BAC will peak and begin to fall.
Depending on how much you’ve had to eat and how quickly you digest your food, your BAC may not reach its highest point for quite a while. Because of this, delaying a breathalyzer or blood test can lead to misleading evidence in a DUI case. This is called the ‘rising blood alcohol defense.’
For example, say you drive home immediately after a large meal and two glasses of wine. An officer pulls you over for expired registration tags and discovers an outstanding warrant. You are taken down to the station and, while there, given a blood alcohol test. It shows a BAC of .08. You may argue that when you were operating the vehicle, your BAC was within acceptable limits and only rose to impermissible levels afterward.
DUI laws are different from state to state. While some allow this defense, others define a ‘per se DUI’ as having a BAC of .08 percent or more within a specific time (typically, two or three hours) of operating a vehicle. If you do intend to present this type of scientific evidence, it’s important to get a medical expert to testify.
How Fast Is Alcohol Metabolized Over Time?
In practical terms, how long does it take to bring down your blood alcohol level to legal limits? Although the metabolic rate of alcohol is not always a constant progression, a reasonable estimate is that BAC drops about .015 per hour. How long it will take you to drop below .08–the legal driving limit in all states except Utah (.05)–depends on how much you have consumed.
Unfortunately, there are no proven ways to speed up this process. An alcohol metabolism chart or phone app can help you estimate your BAC based on your weight, gender, and amount you have consumed.
Facing DUI Charges?
If you have been charged with a DUI, then How fast is alcohol metabolized? may be more than just a theoretical question. You may be able to challenge DUI charges based on your circumstances and biology. Consult with an attorney to evaluate your options.
Legal Disclaimer: This article contains general legal information but does not constitute professional legal advice for your particular situation and should not be interpreted as creating an attorney-client relationship. If you have legal questions, you should seek the advice of an attorney licensed in your jurisdiction.