On One Glass Too Many
Why your hangover has nothing to do with how much you drank. Not exactly, anyway.
A note: shoutout to my friend Mia who recently reclaimed the right to use hyphens on Substack, and so, instead of asking Claude to avoid them, I’m just going to do the same ;) . JK — I actually enjoy writing.
I still remember my first team dinner at my firm. We were at one of those places where the wine list comes before the food menu, everyone had ordered something, and when the waiter got to me I looked around the table and then back at him and said I was fine with water.
My face went completely red. I felt immediately boring, like I had just signed a lease on the most predictable personality at the table, and I prayed no one made a big deal out of it or asked me to explain.
Not because I don’t drink. I love a good glass of red wine. But I genuinely had no idea whether some glasses that night would mean I showed up fine the next day or whether the hangover would make me 0% productive, and I had too much work to gamble on it.
The part I could not explain, to them or to myself, was why I did not know. I have had four drinks on a Saturday and felt basically fine on Sunday. I have had two glasses of wine on a Wednesday and lost the next day completely. At some point I started keeping notes, but the notes did not help. A friend texted me a few weeks ago, Sunday morning, from her couch. She had had what she described as a completely normal Friday, same dinner she has had a hundred times, and spent the entire weekend horizontal. Her word for how she felt is not printable.
The math does not track, and the math is supposed to track.
Let’s start with the basic question: what is actually a hangover? It turns out that annoying headache, stomachache, or lack of will to live is not measuring how much you drank. It is measuring how high your blood alcohol peaked. A 2016 study in Psychopharmacology found that peak blood alcohol concentration is a stronger predictor of next-day severity than drink count — reassuring and slightly inconvenient. On nights when your blood alcohol peaks higher, because you ate less, slept less, or your body was clearing more slowly than usual, the hangover is worse even if the glass count was the same. That friend who had a completely normal Friday and spent the weekend on her couch did not drink more than usual. She peaked higher than usual.
The National Institute on Alcohol Abuse and Alcoholism considers up to 3 drinks in a single occasion to be within low-risk parameters for women. Three drinks at a team dinner. That sounds like a reasonable evening. What they do not say loudly enough is that the unit they are counting (the standard drink, 14 grams of pure alcohol) was calibrated on a 70-kilogram man. Women were never the reference body, I guess they failed to mention that part.
In 1990, Mario Frezza and his team at the University of Padua showed exactly why this matters. They measured gastric alcohol dehydrogenase activity in men and women and found that women have significantly less of it. This enzyme begins breaking down alcohol in the stomach lining before it reaches your bloodstream. In women, so little of it is active that a meaningful portion of each drink passes through essentially unprocessed. Men neutralize substantially more before it becomes a problem. Body composition compounds this further: women carry roughly 52% body water by weight compared to approximately 61% in men, because fat tissue holds almost no water and women carry proportionally more of it. Same drink, smaller pool to dilute into, higher concentration in the blood — information that would have been useful at approximately every dinner party you have attended. Women were not being dramatic. The math just did not account for them.
Frezza published this in 1990. We are in 2026 yet the standard drink has not changed. Nobody updated the guidelines.
So: what does one drink actually cost a woman? The Frezza findings get you part of the way there. They explain the gap between women and their male colleagues at the same table. They do not explain why women are different from themselves week to week, which is the question most women are actually googling mid hangover.
For women with a natural cycle, part of that answer is phase. During the luteal phase, the two weeks after ovulation when progesterone is elevated, alcohol clearance appears to slow. Same drink, longer in her system, higher peak. If you read my first article, you know I do not have a cycle to track — yet. But for those who do, their phase is a more useful data point than their drink count. And for women on hormonal contraception, the equation shifts again: a study in Alcoholism: Clinical and Experimental Research found that women on the pill eliminate alcohol roughly 13% more slowly than women who are not. Nobody tells you this when they hand you the prescription; I have also checked the pamphlet. The research on this is, for the record, very thin — which is itself a data point.
Disregarding sex, the hangover product market is a very long list of things that promise to cure the problem of having “enjoyed yourself” a little too much the night before. And, I am not shy to admit that I have tried most things that get whispered around: ginger tea for your gut, a spoonful of olive oil before the first drink, a glass of milk, coconut water and electrolytes in every format they come in. To my surprise, there are people who take it one step further and show up voluntarily to a Saturday morning IV drip, which is my inner child’s worst nightmare now available as a service with good lighting.
In what can only be described as a triumph of human logic, we have taken the body’s most direct signal that alcohol is a poison and concluded the problem is the morning after. Which only raises the question: what is the actual price of getting rid of it?
If you believe in girl math, one fewer drink might just even out against the cost of the cure. In this search for something that would actually pass this test, a friend recently mentioned ZBiotics, which is a probiotic you drink before you drink, and learning about it made me genuinely curious.
Zack Abbott has a PhD in microbiology and has spent eight years on one very specific problem: a probiotic that addresses the actual cause of a hangover rather than negotiating with the symptoms the morning after.
Abbott co-founded ZBiotics in 2016 around the insight that the main driver of hangovers is not alcohol itself but acetaldehyde, the compound your liver converts alcohol into as a first step in processing it. Your liver handles acetaldehyde efficiently. Your gut does not. Acetaldehyde that makes it into the gut accumulates, and that accumulation is what you are feeling the next morning. Abbott engineered a strain of gut bacteria (B. subtilis) to produce the same enzyme the liver uses, so it starts breaking down acetaldehyde before the buildup happens. ZBiotics has sold eight million shots. It is, to its own apparent delight, proudly GMO.
I have not tried it, and I will not recommend something I cannot personally verify. What I can say is that the underlying biology is published and peer-reviewed, and addressing the input rather than negotiating with the output is at least doing the math in the right order. Nonetheless, I cannot tell you whether it works at the same rate in a female body given everything above. ZBiotics has not published sex-specific data on this. Abbott, if you ever read this: somewhere in your Series A, one of those study variables can afford to look at sex.
And so, here is my wisdom to you: your limit is not a number. It is a function of at least five things that shift week to week: the enzyme activity you were born with, body composition, food timing, hydration, and your hormonal baseline on any given night. Wine on a well-rested Tuesday is not the same drink as two glasses on a depleted Thursday after a long week of work.
So, what do I do? I still do not have a formula. I am not sure one exists for five simultaneous, oscillating variables, and I suspect that if it did, it would end with a recommendation none of us are looking for. What I have now is a better set of questions to ask before the waiter gets to me, a better answer for colleagues who are curious about why I skip drinks on weekdays, and the knowledge that the math was never going to work the way I was running it.
Works Cited
Frezza, Mario, et al. “High Blood Alcohol Levels in Women.” New England Journal of Medicine, vol. 322, no. 2, 1990, pp. 95–99. doi:10.1056/NEJM199001113220205
Warren, Jasmine G., et al. Frontiers in Global Women’s Health, 2021. doi:10.3389/fgwh.2021.745263
Jones, M.K., and B.M. Jones. “Ethanol Metabolism in Women Taking Oral Contraceptives.” Alcoholism: Clinical and Experimental Research, vol. 8, no. 1, 1984, pp. 24–28. doi:10.1111/j.1530-0277.1984.tb05026.x
Van de Loo, Aurora, et al. “Urine Ethanol Concentration and Alcohol Hangover Severity.” Psychopharmacology, vol. 234, no. 1, 2017, pp. 73–77. doi:10.1007/s00213-016-4437-0
Heels Off is a weekly newsletter from Daniela Fajardo. Heels off, guard down, no bull****. Just straight talk about what these big, demanding lives ask of our bodies, and how to pay less for them.