Blood Alcohol Concentration

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

Body size determines the amount of space that alcohol has to spread 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 spreads more into muscle than fat because muscle tissue has more blood flowing through it. This means that an individual’s muscle to body fat ratio will impact their BAC, as it is connected to the amount of blood available for alcohol to enter. For example, someone with a higher percentage of body fat will experience a faster increase in BAC, as alcohol will become more concentrated in the blood of their muscle tissue.

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 spread 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.

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.

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.

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

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.

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.