“When you came to our school you told us that pretty well everything about alcohol was worse for women that it was for men, particularly around BACs for driving, and that we need to be far more careful when it comes to drinking. Why can’t women drink as much alcohol as men?”
Although this may seem like some sort of male conspiracy the truth is that biology does matter when it comes to drinking alcohol. Studies show that females are likely to experience the harmful consequences of drinking sooner and at lower levels of alcohol exposure than men. This is due to some important physiological differences that affect the way the body processes alcohol.
If a man and a woman were to drink the same amount, the woman’s blood alcohol concentration (BAC) will almost always be higher, putting them at greater risk of harm. There are many reasons why this might occur but researchers have identified the following three key factors that lead women to be more quickly affected by alcohol and more vulnerable to its effects:
Body size and fat: Women tend to be smaller than men, meaning ‘drink for drink’ the same amount of alcohol is going into a smaller body and so can have a greater effect. Their bodies also contain less water and more fatty tissue than a man’s. It’s estimated that a male body is composed of 55-65% water, whereas a female has only 45-55%. Fat retains alcohol while water dilutes it, and so alcohol remains at higher concentrations for longer periods of time in a woman’s body, exposing her to more alcohol and potentially more damage.
Enzymes: Women have lower levels of two enzymes that metabolise alcohol in the stomach and liver – alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Due to these lower levels, they’re unable to break down alcohol as effectively, resulting in more alcohol being absorbed into their bloodstream.
Hormones: Changes in hormone levels during the menstrual cycle may also affect how a woman metabolises alcohol. Research has found that one week prior to menstruating, females maintain their peak level of intoxication for longer periods of time, i.e., they stay drunk for longer. This same effect is also found when people use birth control pills, i.e., medications containing estrogen.
It’s important to remember that even when consumed responsibly, alcohol use poses unique risks to all women. Due to their inability to process alcohol as effectively as men, women are much more vulnerable to alcohol’s harmful effects and face a greater risk of developing liver disease, heart disease, cancer and particularly breast cancer, than men who drink similar amounts or even more. It’s unlikely that this information is going to stop women from drinking. What is hoped, however, is that we can encourage those who do choose to drink to develop as healthy a relationship with alcohol as possible, e.g., don’t drink a lot, don’t drink regularly and try to have regular breaks.
First published: May 2015
Reviewed and updated: February 2025
