Just as a given amount of alcohol effects people differently, men and women absorb alcohol differently. Women reach a higher BAC faster because they have less water in their bodies and more adipose tissue (fat), which is not easily penetrated by alcohol. Because of their lower proportion of lean body mass, women absorb alcohol more rapidly than men. Women also have lower total body water content than men of comparable size. After alcohol is consumed, it diffuses uniformly into all body water, both inside and outside cells. Because alcohol mixes with body water, a given amount of alcohol becomes more highly concentrated in a woman’s body than in a man’s.
Alcohol also affects women differently than men due to the fact that women metabolize alcohol more slowly. Women have less of the ADH enzyme. This causes a larger proportion of the ingested alcohol to reach the blood system prior to being converted to acetate. Women experience fluctuations in hormone levels during their menstrual cycle that may affect the rate of alcohol metabolism. This makes a woman more susceptible to elevated blood alcohol concentrations at different points in the cycle. They will experience their highest BAC during their premenstrual stage. Since body temperature is also elevated at this time, and during menopause, a women’s true blood alcohol level may be overstated because breath testing in California assumes that the temperature of expired breath is 34 degree Celsius (convert to Fahrenheit)- every degree above average will result in a 6.9% false high. In addition, there is also evidence that a woman taking birth control pills will absorb alcohol faster, resulting in higher BAC levels.
It does not help that field sobriety testing and chemical testing are not developed for women. Breath testing machines are not designed to accurately test a woman’s blood alcohol level. The breathalyzer was designed for an average man’s lung capacity, which is obviously much different than that of a woman’s. This could cause a breathalyzer to read at a higher level.
