Factors Affecting Blood Alcohol Concentration (BAC)

Who metabolizes alcohol faster: A man or a woman?

  If a man and woman drink the same amount of alcohol, the woman will have a higher BAC since:

  • Women have fewer alcohol dehydrogenase enzymes to break down alcohol in the stomach
  • Women typically have a higher percentage of body fat and a lower percentage of water

  Blake JS. Nutrition & You. San Francisco, CA: Pearson Education, Inc.; 2008

Does fat/muscle composition affect BAC?

  Absolutely! The less you weigh, the more you will be impacted by the effects of alcohol. If two individuals weigh the same, a person with a higher fat percentage will have a higher BAC compared to a person with a high muscle mass because:

  • Fat is water insoluble, and muscle is water soluble
  • A higher fat composition has decreased surface area for alcohol to be distributed throughout the body compared to individuals with a lower percentage of body fat

  National Institute on Alcohol Abuse and Alcoholism. (1999). Are women more vulnerable to alcohol’s effects? Retrieved from: http://pubs.niaaa.nih.gov/publications/aa46.htm

What foods are best to eat before drinking?

  • Having food in your stomach will help slow down the rate at which alcohol is absorbed into the bloodstream resulting in a lower BAC.
  • Consuming foods high in carbohydrates, such as bread or pasta, will NOT help absorb the alcohol. Instead, consuming a balanced meal of proteins, fats and carbohydrates is best to help fuel the body.
  • Eating AFTER alcohol consumption will NOT help since the alcohol is already in the bloodstream. Once a person has consumed alcohol, only time will make a person sober. Taking a shower, eating, drinking coffee, or exercising will not help make someone sober.

  Rethinking Drinking - National Institute on Alcohol Abuse and Alcoholism. (2014). Tips to try. Retrieved from: http://rethinkingdrinking.niaaa.nih.gov/Strategies/TipsToTry.asp

Feeling Tired or Stressed? This can impact your BAC!

  • Being tired or stressed can result in a higher BAC. Choose not to drink or reduce your consumption since:
    • The liver functions at a decreased rate when stressed, tired or ill and alters the body’s ability to process alcohol causing a higher BAC.


  • Alcohol is not a stress reliever:

    • Research shows alcohol consumption causes physical responses similar to the body’s stress response.
    • This is counterproductive since alcohol creates the exact symptoms a stressed person is trying to reduce.


  • When someone drinks to have a good time and de-stress, the effects of alcohol are amplified due to:

    • The person’s expectations that alcohol will help them relax and have fun.
    • People report feeling relaxed and euphoric starting at a BAC of just 0.02. At a BAC above 0.06, mood begins to diminish.


  National Institute on Alcohol Abuse and Alcoholism. (2012). Alcohol alert: The link between alcohol and stress. Retrieved from: http://pubs.niaaa.nih.gov/publications/AA85/AA85.htm

How does alcohol affect diabetes?

  Alcohol can cause hypoglycemia immediately after drinking or up to 24 hours after drinking. Practice caution when drinking:

  • Check blood glucose before you drink, before bed and 24 hours after drinking.
  • Symptoms of alcohol poisoning and hypoglycemia can be similar; always wear an I.D. that notes you have diabetes to ensure you receive the proper assistance.
  • Do not drink on an empty stomach; eat a balanced meal.
  • Do not drink when your blood glucose is low.
  • Do not count alcohol in meal plan as carbohydrate choice.
  • Stay hydrated by drinking water, diet soda or iced tea.
  • Choose calorie-free drink mixers like water or diet soda.

  American Diabetes Association. (2014, June 6). Alcohol. Retrieved from: http://www.diabetes.org/food-and-fitness/food/what-can-i-eat/making-healthy-food-choices/alcohol.html

How can birth control or menstruation affect my BAC?

  • Hormonal differences between men and woman can affect the body’s ability to process alcohol. In fact, women will experience higher BAC’s in the days before menstruation or if they are taking a hormonal birth control.

  Governor’s Council on Impaired Driving. (2015). Understanding bac (blood alcohol concentration) levels. Retrieved from: http://wygcid.org/Understanding_BAC.html

How can medications and other drugs impact my BAC?

  • It is important to know how alcohol will interact with other medications. Potentially dangerous alcohol-drug interactions can occur with very small amounts of alcohol.
  • Consult with a physician before mixing any medication with alcohol. When talking to a doctor about alcohol intake, remember to discuss the amount of alcohol you plan to consume, not just alcohol use in general.
  • Allergy, cold and flu medicines, herbs and supplements, anxiety medications, epilepsy medications, diabetes medication, sleep medications, birth control and antibiotics can all intensify the effects of alcohol.

  U.S. Food and Drug Administration. (2013, September 25). Drug interactions: What you should know. Retrieved from: http://www.fda.gov/Drugs/ResourcesForYou/ucm163354.htm

How Does Tolerance Affect BAC?

  • Someone with a high functional tolerance can be impaired before feeling any physical effects from alcohol consumption.
  • BAC is UNAFFECTED by functional tolerance. Someone with a high tolerance may not show signs of physical impairment and might not ‘feel’ drunk but would still have alcohol in the bloodstream resulting in a high BAC.
  • A high tolerance might lead to risky decision making. For example, someone may think they are not drunk and choose to drive a car.

  Rethinking Drinking – National Institute on Alcohol Abuse and Alcoholism. (2014). What is a standard drink? Retrieved from: http://rethinkingdrinking.niaaa.nih.gov/WhatCountsDrink/WhatsAstandardDrink.asp