Have you ever heard of the “One Drink an Hour Rule?” According to this rule, if have only drink per hour, your blood alcohol level (BAC) will remain under the legal DUI limit of .08%. (One drink is roughly defined as 1 1/4 ounce of hard liquor, one beer or one glass of wine.) Is this true?


Well, it depends. There is actually no hard and fast rule and a variety of factors can affect your BAC. Things such as your weight, whether you’re eating while you are drinking, and whether you are male or female will influence your blood alcohol level. For example, a female who weighs 110 pounds and has only two drinks in two hours will almost certainly have a BAC of over .08%, while a man weighing over 210 pounds might not register a BAC of over .08% until he has had four drinks during those two hours. Different body types process alcohol differently for several reasons, including body fat content and the concentration of the liver enzyme that breaks down the alcohol. Hormones may also be a factor.


It helps to understand how your body metabolizes alcohol. As alcohol enters your body, small blood vessels carry it to your bloodstream. It is then metabolized by your liver, where it is broken down by enzymes. In general, the liver can process a one drink an hour. But if you drink more than your liver can metabolize, the alcohol accumulates in your blood and body tissues until the liver can do its work. That is why you get much drunker if you have several drinks in a short period of time versus several drinks over a longer period of time.


Perhaps you have had the experience of feeling unusually tipsy after having only one drink before a meal. When you drink on an “empty stomach,” the alcohol is quickly absorbed into your bloodstream, whereas if you have a full stomach, that absorption is slowed down. Because the absorption of the alcohol into your bloodstream is slower when you have a full stomach, there will be a lower blood alcohol concentration in your blood. This doesn’t mean you wouldn’t get a DUI if you took to the wheel after drinking during a big meal, it just means that it might take a bit longer and a bit more alcohol for your blood alcohol level to reach the legal driving limit of .08%. However, this is only one factor and your particular BAC will be influenced by other factors including your weight, your metabolism, and the amount of food you consume.


It is safe to say that if you are a small woman, after the first drink, the one drink an hour rule will almost never apply. However, the larger your body mass, the more relevant this rule becomes. That being said, there many factors that can affect how much alcohol is concentrated in your blood. With each drink, even if it’s only one per hour, you will become increasingly impaired. The best rule is to simply not drink if you are driving.


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