Fights, meltdowns, breakups, arrests and people puking across the bar. In his seven years of bartending in Kansas City at Union Station, the Power & Light District, Westport and Ameristar Casino, bartender Eli Zajac has seen it all.
For some people, it might happen a few times a year. For others, it’s every weekend.
“I feel like people will use any excuse to drink,” Zajac said.
Not much is known about extreme binge drinking because it’s hard for scientists to measure. When most people who drink an excessive amount are asked to recall details the next day, they don’t remember, said Denis McCarthy, clinical psychologist and professor at the University of Missouri.
But now, researchers at Mizzou, including McCarthy, are using smartphones and portable breathalyzers to learn more.
Many who extreme binge drink don’t have an alcohol use disorder, which is a medical disorder in which someone can’t stop or control alcohol use despite negative consequences and includes what used to be known as alcoholism. But they may be at higher risk for developing one, McCarthy said.
“This phenomenon of heavy drinking fits well with modern tech methods of collecting information from people as they go through their daily life,” McCarthy said.
“This is really needed and can answer questions we have not been able to answer because the organ that has to report on what is going on — the brain — is the organ that is impaired.”
What is extreme binge drinking?
As more people get COVID-19 vaccinations and social distancing regulations ease, they will likely return to social drinking. About 13% of adults in the U.S., almost 32 million people, participated in extreme binge drinking at least once in the previous year, according to a 2013 National Institute on Alcohol Abuse and Alcoholism study.
During the pandemic, the frequency of alcohol use and amount of binge drinking increased, according to a study published by JAMA Network Open. Women in particular had a 41% increase in days of binge drinking when compared to 2019.
While the long-term effects of drinking alcohol are pretty well known, such as damage to the digestive system, liver, cardiovascular system and brain plus increased risk of cancers, the physical effects of a single drinking episode aren’t as apparent.

Excessive alcohol use is a public health issue both in Kansas and Missouri. In Kansas, 16.5% of adults binge drink, and in Missouri, 17.7% of adults binge drink. It is estimated that excessive alcohol consumption costs Kansas about $2.1 billion a year and Missouri $4.6 billion a year in costs related to loss in workplace productivity, health care expenses, criminal justice expenses, motor vehicle costs and property damage.
Right now, there is a gap in research on binge drinking. Blood alcohol concentration levels at or above 0.08% — the legal driving limit — traditionally have fallen under a wide “binge drinking” umbrella. But extreme binge drinking, at a BAC of 0.16%, is twice the amount of the lower end of “normal” binge drinking.
It’s hard to quantify extreme binge drinking without measuring BAC. On average, a person reaches a BAC of 0.16% after drinking 10 to 12 drinks in a two-hour period, said McCarthy. Those variables, however, can change based on a person’s size.
When drinking continues for longer than two hours, calculating how many drinks constitute extreme binge drinking gets more complicated. People vary a lot in terms of how quickly they can eliminate alcohol from the bloodstream, depending on their weight, body fat and how much they continue drinking, McCarthy said.
Zajac sees dramatic differences in how customers react to drinking at this level.
“I’ll serve five old fashioneds, which is 9 ounces of whiskey, and I’ll see these 50-year-old men get up perfectly fine. Not stumbling, not slurring,” he said. “Anyone young, if you give them three to four shots, they’re lit. And that’s just them starting to drink.”
The risks of consequences increase as people drink more. Extreme drinking, even if it only happens twice a year, can have lasting negative impacts, McCarthy said.
“Whether they get in trouble with their friends, they get in trouble with their spouse, they don’t perform as well in school, they miss a day of work,” McCarthy said. “Those are the types of moderate-level consequences that can significantly affect someone’s life.”
As a bartender, Zajac has tried not to over-serve drunk customers. Bartenders can be held liable if a customer gets into an accident while driving under the influence.
But Zajac also knows what it’s like to extreme binge drink. A few years ago, he went to a Kansas City Chiefs game and split a handle of alcohol — a bottle that contains 39 shots of liquor — with a friend.
“Apparently, I was headbutting a windshield,” he said. “You wake up, and people tell you the things you do. It’s like a character in a story because I don’t have any memories of this.”
How researchers will record the data
Traditionally, researchers study drinking through a data diary, where participants fill in details of their night the following day. But this doesn’t work well for extreme drinking.
McCarthy has found that people are able to reliably record what they are doing in the moment while excessively drinking, but not the next day.
So the new Mizzou study — funded by a five-year, $2.5 million grant from the National Institutes of Health — will use digital methods, like sending out surveys for participants to fill out while they are drinking and a breathalyzer that connects to their smartphones.
This will allow the study to recruit people from across Missouri rather than being limited to people who can come to a physical lab space.
The study is recruiting people ages 21 to 29 and is paying the participants. The lab has been recruiting people through mail and phone calls, McCarthy said.
But giving participants breathalyzers could come with issues, McCarthy said. Younger drinkers might gamify the breathalyzers to see how high they are able to get their BAC, or someone might drink more because they know they haven’t reached the legal driving limit yet.
It’s normalized. If you tell someone you blacked out, or woke up puking, 99% of your friends will say, ‘So it was a good night then.’
eli zajac, bartender
Ethically, researchers need to try to protect participants from these kinds of behaviors, so the breathalyzers are modified to record data but not display it to the participants.
The researchers hope they can gain more information surrounding people’s motivations for extreme binge drinking and how often they do it. It’s likely people drink higher amounts and more often than is currently suspected, McCarthy said. Researchers want to find out what separates a binge drinking day from a non-binge drinking day.
“For people who do this, why did they do it this Saturday and not the Saturday before?” McCarthy said. “What were the contextual variables? Who were they with, where were they, how were they feeling?”
More people seem to extreme binge drink when they have an excuse, like on Cinco de Mayo or St. Patrick’s Day, rather than on a Tuesday night, Zajac said. But some people will use normal events, like brunch, as an excuse to black out.
“It’s normalized,” Zajac said. “If you tell someone you blacked out, or woke up puking, 99% of your friends will say, ‘So it was a good night then.’”