Dear Science,

Why is it that some nights I can have two beers after eating a solid dinner and feel super tipsy, and other nights have two martinis after barely eating and barely feel anything? I've heard that alcohol affects women differently at different times of the month (I am a woman) because of hormone fluctuations, but I have no idea if that's true. Thank you!

An Unpredictable Drunk

Before we launch into an exploration of lady times and liquor, let us take a moment to appreciate the liver. Aside from the moments it's trying to kill you, your liver is quite possibly the organ that loves you the most—keeping you from bleeding to death; devouring and rendering harmless almost all toxins you eat, drink, and breathe; and helping you digest fat. Life with a sick liver is not a good place to be. When it becomes sickly, your liver shrivels up, becoming tough and fibrous—rather than its healthy squishy and brown cheer. Your belly fills up with body fluids; veins in your neck, belly button, and rectum swell; and you run a decent chance of dying from massive bleeding from your throat. In short: Be good to your liver—or else.

For your question, we must consider the toxin-clearing efforts of the liver. A lovely family of proteins—the cytochrome P450s—make it their business to fuss with just about anything floating in your blood. These proteins use an angry iron ion to splat oxygen atoms onto toxins—in a sense burning them. Different P450 proteins handle different toxins. As you'd expect, if you flood your body with toxins, the liver tries to respond in kind by increasing the production of these poison clearers. Conversely, some toxins target and block some of the P450 proteins—protecting themselves from the liver's ire. Into this lovely battle enter alcohol and the sex hormones.

Alcohol is mostly processed through its own special mechanism, eventually becoming vinegar (that your cells gleefully consume as food). The P450 proteins, however, chip in on this process. How do lady cycles fit in with this? Estrogen and progesterone both fuss with the expression of the P450 proteins in your liver, turning some up and others down. The overall changes mean that in the first half of the menstrual cycle (when progesterone is king), your alcohol-clearing powers are different than the later half (of estrogen predominance). Science would expect your alcohol tolerance to switch with the time of the month for this reason.

In the spirit of empiricism, work with your observation. Keep track of basal body temperature (to figure out where you are in your cycle) and how many drinks it takes to put you down. Are you more affected during the progesterone or the estrogen time? Science wants to know. Write back with the results.

Oxidizingly yours,


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