Even in Paris's hard-drinking intellectual circles, French philosopher and feminist icon Simone de Beauvoir found that a glass of wine hit harder than expected. De Beauvoir once joked that two glasses left her feeling quite dizzy, long before any existential debates began.

Decades later, science can explain why: Women's bodies process alcohol differently from men's — often faster and more intensely — and women's brains also respond more strongly to its rewarding effects, even when drinking the same amount as men.

How alcohol moves through the body

Alcohol affects the body almost immediately. Before it hits the stomach, taste buds signal the brain, causing small changes in heart rate, blood flow, and brain chemistry to get the body ready.

When you swallow alcohol, a little is absorbed in the stomach, but most moves to the small intestine, where it quickly enters the blood.

Some of it is broken down in the stomach and liver by an enzyme called alcohol dehydrogenase (ADH), a process known as first-pass metabolism (FPM).

In 1990, researchers gave 20 men and 23 women the same amount of alcohol — adjusted for each individual's body weight. The women drank the same amount as the men — but their bodies filtered out less alcohol early on, so more of it entered the bloodstream, resulting in higher blood alcohol levels on average.

But intoxication isn't only about how fast alcohol enters the blood. What happens next — in the brain — also differs by biological sex.

Sex differences and the body weight debate

Scientists broadly agree that women, on average, feel the effects of alcohol sooner. Where they disagree is on why this is the case.

Rainer Spanagel, a German neuropharmacologist and addiction researcher, cites body weight as the dominant factor. "It's not the enzyme," he told DW, "it's body weight."

Ethanol, Spanagel explained, distributes evenly throughout the body's so-called compartments — including the brain and organs.

Smaller bodies mean smaller compartments. "If a man drinks half a bottle of wine, and a woman drinks the same, the same amount of ethanol accumulates in a smaller body."

But other researchers argue that weight alone does not explain everything about alcohol's effect on women.

Beyond size: enzymes, body composition, and the brain

Alcohol starts working the moment it's consumed and keeps influencing the body well after it hits the brain.

"Maybe not so much body weight or size, but composition has a bigger difference in sex-differences," said Edward Scotts from Louisiana State University, who studies neurobiological mechanisms of alcohol use disorder.

Women usually have more body fat and less water than men, so alcohol becomes more concentrated in their blood.

"That's in addition to the ADH difference," Scotts added. ADH, he said, was a crucial early filter.

"As you drink the alcohol, it goes to your stomach first, and you have some ADH within your stomach — but men have more than women," he said. "Therefore, men are able to metabolize it much faster at the initial stage."

This intrinsic difference helps explain why health guidelines define binge or hazardous drinking differently for men and women.

Jill Becker, a researcher at the University of Michigan, who specializes in sex-based differences in the brain and behavior, said metabolism and absorption shape intoxication but that everyday drinking rarely accounts for this process.

"A glass of wine is the same size whether it's a man or a woman [drinking it]," Becker said. "I don't ask her how much she weighs and give her less."

As a result, women often receive a higher dose relative to their bodies before the enzymes even begin to act.

Alcohol addiction in women or how alcohol affects the brain's reward systems

Once alcohol reaches the brain, women show a phenomenon known as telescoping: a markedly faster progression from use to dependence. "They become addicted more rapidly and consume larger quantities in a shorter period of time," said Becker.

Becker's observation is supported by research showing that women move more quickly than men from first use to severe alcohol‑related problems and to treatment entry, often after fewer years of drinking and lower lifetime consumption.

Clinical studies in the 1980s, 1990s, and 2000s consistently found that women experience shorter intervals between key drinking milestones, despite typically beginning regular use later in life than men.

Hormones play a role, too. Estradiol, the primary hormone produced by the ovaries, enhances dopamine release in the brain.

Alcohol indirectly increases dopamine — and estradiol amplifies its effect.

"During ovulation, women tend to like substances more," Becker explained, increasing the likelihood of their drinking more alcohol.

And stress also matters. Women are more likely than men to use alcohol to self-medicate for anxiety or depression.

"Certainly, some men will self-medicate," said Becker, "but a larger percentage of women are taking alcohol and drugs to self-medicate."

Rethinking equality at the bar

For Becker, science has social implications. "I'm a woman of the 1970s, second-wave feminism," she said. "There was a strong belief [then] that we had the right to drink like men."

That belief was rooted in equality — but biology can complicate equality.

"Women need to be aware that not only are they going to get drunk more rapidly if they drink shots with the guy standing next to them," said Becker, "but that the long-term consequences can also be more devastating."

The takeaway is not about restriction, but understanding. Alcohol does not hit harder because women are weaker drinkers. It hits harder because women's bodies, enzymes, hormones, and brains respond differently, long before tolerance ever comes into play.

Edited by: Zulfikar Abbany