There are a number of biological differences between the way that women and men process alcohol. These differences contribute to a higher blood alcohol level in women, which may increase the risk of negative consequences.
Women have less body water in which to dilute the alcohol consumed, so a woman’s blood alcohol level (BAC) will be higher than a man’s BAC even if they weigh the same.
The weight of a person greatly affects the distribution of alcohol in the bloodstream; the smaller the person, the less room for alcohol to distribute itself. This means that the blood alcohol level of a small person will be higher than that of a larger person.
Women have smaller quantities of the enzyme alcohol dehydrogenase that breaks down alcohol in the stomach. A woman will absorb about 30% more alcohol into her bloodstream than a man of the same weight who has consumed an equal amount, which results in greater intoxication for the woman.