What is the only effective method to reduce your bac

Please note: This information does not constitute legal advice and should not be relied upon in this way. The information is correct at the time of publication. For information specific to your situation contact a legal aid service in your state or territory.

Definition

Blood alcohol concentration (BAC) refers to the amount of alcohol present in the bloodstream.

A BAC of 0.05% (point 0 five) means that there is 0.05 grams of alcohol in every 100 millilitres of blood.

Factors affecting the BAC

The more a person drinks, the higher their BAC, however, two people who drink the same amount of alcohol might register quite different BACs. This is due to a variety of factors including body size, whether or not they have eaten recently, percentage of body fat, whether they are male or female and whether or not they have drunk before.

Body size

A smaller person will have a higher BAC than a larger person for the same amount of alcohol consumed, because the alcohol is concentrated in a smaller body mass.

Empty stomach

A person with an empty stomach will reach a higher BAC sooner than someone who has just eaten a meal, because food in the stomach slows the rate at which alcohol passes into the bloodstream. However, eating before drinking does not prevent intoxication.

Body fat

Alcohol is not absorbed into fatty tissue, therefore people with a greater proportion of body fat will develop a high BAC more quickly than those who have lower proportions of fatty tissue. This occurs because the alcohol becomes concentrated in the smaller mass of non-fatty tissue.

Gender

Women’s bodies, being generally smaller than those of men and with a higher ratio of fatty tissue to lean muscle, will absorb alcohol more quickly than men’s bodies do. This means that a woman drinking the same amount of alcohol as a man, will develop a high BAC more quickly than the man will.

Inexperience

Less experienced drinkers have a lower tolerance to alcohol and so their BAC is likely to rise more quickly than it will in more experienced drinkers.

Driving

Alcohol is a depressant drug. It slows down the activity of the central nervous system, including the brain.

Alcohol could affect your driving by causing:

• impaired vision
• reduced reaction times
• reduced concentration and vigilance
• feeling more relaxed and drowsy, which may cause a driver to fall asleep at the wheel
• difficulty in understanding sensory information
• difficulty doing several tasks at once (e.g. keep in the lane and in the right direction, while concentrating on other traffic)
• failure to obey road rules
• over confidence, which may lead to risk taking.

The hangover effects of alcohol, the next day, can make it hard to concentrate and drive safely, and might cause you to fall asleep while driving.

A person who has been drinking alcohol may think that if they are especially careful, they will be able to drive safely. However, the alcohol may have affected their view and experience of reality. Their actions and responses may be quite different to what is actually needed, but they may be unaware of how much their driving skills have been affected.

Tips for driving safely

If you intend to drive, the safest option is not to drink.

Keep track of how much you drink

If you do decide to drink, keep track of how much you drink, by monitoring the number of standard drinks you consume each hour.

Some people may need to drink less to keep their blood alcohol concentration (BAC) under 0.05 and drive safely. Find out more about BAC.

Limit your drinking

• Start with a non-alcoholic drink, and have a non-alcoholic drink (a “spacer”) every second or third drink.
• Avoid topping up your glass, as it makes it difficult to keep an accurate track of how much you’ve had.
• Drink low-alcohol drinks, and avoid mixed drinks, like cocktails, as it is difficult to tell how much alcohol they contain.
• Avoid drinking in shouts or rounds, so you don’t feel pressured to keep up with your friends.
• Sip drinks, and avoid salty snacks or other food that increase thirst.

Wait for your BAC to drop before driving

It is important to remember that BAC can continue to rise up up to 3 hours after the last drink was consumed.

The only way to remove alcohol from your system is to allow the body time to process it. Showers, coffee or fresh air will not reduce BAC.

On average, the liver breaks down a little less than one standard drink per hour. Before driving, you should wait at least an hour for each standard drink you’ve had.

Have a back-up plan

If you have too much to drink, be prepared to make other arrangements so you don’t have to drive to get home.

For more information, please click on the Alcohol and Drug Foundation’s (previously Australian Drug Foundation) logo below.

1. Australian Drug Foundation. Blood Alcohol Concentration (BAC). Last updated 8 June 2011. https://www.druginfo.adf.org.au/topics/bac (accessed Feb 2013).
2. Australian Drug Foundation. How does alcohol affect driving? Last updated 27 April 2012. https://www.druginfo.adf.org.au/topics/how-does-alcohol-affect-driving (accessed Jan 2013).

BAC refers to the percent of alcohol in a person's bloodstream. A BAC of 0.10% means that an individual's blood supply contains one part alcohol for every 1000 parts blood. In Texas, a person is legally intoxicated if they have a BAC of 0.08% or higher. Understanding the factors that impact your BAC is an effective way to make informed decisions about your drinking limits and can help you reduce your risk for potential harm while drinking. To learn more about actions you can take to have fun and play it safe, visit this page.

Tolerance and BAC

Tolerance occurs when the body acclimates to the effects of alcohol, due to habitual use. Tolerance does not impact BAC, but rather makes an individual’s BAC feel lower than it actually is. This means that an individual will feel less affected by alcohol, and it will take more alcohol to reach the same physiological response. The development of tolerance doesn’t mean someone can process alcohol more efficiently and BAC levels will still remain the same. This response is an early sign of developing an alcohol dependency.

Factors that impact BAC

Number of standard drinks and rate of consumption

• BAC will rise relative to the number of drinks consumed and how quickly they are consumed.

Body size and composition

• Body size determines the amount of space that alcohol has to diffuse throughout the body. In general, a person with a larger build who drinks the same as a person with a smaller build will have a lower BAC due to the amount of space alcohol has to distribute through.
• Alcohol diffuses more into muscle than fat because muscle tissue has a large amount of blood that flows through it. This means that an individual’s muscle to body fat ratio will impact their BAC, as it correlates to the amount of blood available for alcohol to enter. For example, someone with a higher percentage of body fat will experience a more rapid increase in BAC, as alcohol will become more concentrated in the blood of their muscle tissue.

Testosterone and estrogen levels

• People with higher levels of testosterone generally have more muscle mass and less body fat than people with higher levels of estrogen. Muscle contains more blood than body fat. The larger volume of blood in those with greater muscle mass allows alcohol to dilute more through the bloodstream and BAC to remain lower.
• People with higher levels of testosterone are composed of approximately 55-65% water, whereas people with higher levels of estrogen are composed of about 45-55% water. Alcohol becomes more diluted in bodies with greater volumes of water, resulting in lower BAC levels for people with higher levels of testosterone as compared to those with higher levels of estrogen.
• Individuals with higher levels of testosterone have higher levels of alcohol dehydrogenase, an enzyme that helps break down alcohol. This means that individuals with higher levels of testosterone can more efficiently break down alcohol as compared to individuals with higher levels of estrogen, who have more alcohol enter their bloodstream, resulting in higher BAC levels.
• Research has found that due to changes in hormone levels, individuals who have periods experience slower alcohol metabolism and higher levels of intoxication in the week leading up to their period. Oral contraceptives and other medications with estrogen also slow the rate at which individuals process alcohol.

Additional drugs or medications

• Other drugs and medications, even those prescribed to you, can have adverse effects and unpredictable interactions with alcohol. It is important to ask your doctor if any medications you might be taking have harmful effects when taken with alcohol.

Amount of food consumed

• Food present in the stomach causes the alcohol to move down into the small intestine slower than it would on an empty stomach. While it’s a common myth that food absorbs alcohol like a sponge, it actually causes a “traffic jam” in the body, making the processing of alcohol take longer. This reduces the risk of a rapidly rising BAC level.

Emotional state, mood and level of fatigue

• Alcohol has a more pronounced effect on those who may be fatigued or under stress. Since alcohol is a depressant, someone who is depressed may experience heightened signs of depression upon drinking.

Menstrual cycle

• Research has found that due to changes in hormone levels, individuals who have periods experience slower alcohol metabolism and higher levels of intoxication in the week leading up to their period.

Type of beverage or mixer

• Fruit juices slow down the processing of alcohol because the sugar requires digestion, resulting in a slower rise in BAC. On the other hand, carbonated mixers or drinks can cause BAC to rise more rapidly because the carbonation speeds up absorption.

It is important to note that common strategies used to “sober up,” such as taking a cold shower, sleeping, drinking water and consuming caffeine, do not work to lower BAC. The only thing that can help alcohol leave your bloodstream is time.

Online Calculators

BAC Calculator: Use this calculator to get an approximate BAC level.

Drink Size Calculator: Learn how many standard drinks are in various beverages and sizes of containers.

The Virtual Bar: See how alcohol consumption affects BAC over time.

Sources

Cornell Health. (2019, October 18). Why Biology Matters When It Comes to Drinking Alcohol. Retrieved from https://health.cornell.edu/sites/health/files/pdf-library/Why-Biology-Matters-Drinking.pdf

Office of Substance Use Programs Education & Resources. (n.d.). Tolerance. Retrieved from https://super.stanford.edu/learn/alcohol-drug-info/alcohol-info

Rev. James E. McDonald, C.S.C., Center for Student Well-Being. (2021). Absorption Rate Factors. Retrieved from https://mcwell.nd.edu/your-well-being/physical-well-being/alcohol/absorption-rate-factors/

UCSB Prevention and Wellness Services. (2003, November 13). Alcohol 101: Gender Differences. Retrieved from https://adp.sa.ucsb.edu/sites/default/files/2021-05/alcohol_-_genderdifferences.pdf

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