Why does coffee make you pee so much?

To paraphrase the old beer saying, you’ll never buy a cup of beer. coffee – you just rent it. While standing in line to use the restroom at your favorite coffee shop, you may wonder why this particular drink affects your bladder so much.

Find out what the experts have to say about this journey, from that first delicious sip to the mad dash to the toilet and every stop in between.

Everything you swallow goes straight to your stomach. Depending on how much is already in there—if it’s your first sip of the day or you just had a big lunch—it can hang around in your stomach for anywhere from five minutes to an hour.

Liquids are digested faster than solid foods, so your body immediately goes to work on a cup of coffee on an empty stomach, sending it through the intestines, kidneys and on its way to the bladder. And this is what makes caffeinated coffee different from some other drinks, according to Lisa AndersonAssistant Professor, Department of Integrative Biology and Physiology, University of Minnesota.

“The small intestine uses osmosis to absorb fluid, using energy to pull in sodium and other electrolytes so that the fluid follows these particles,” Anderson told HuffPost. “In caffeinated coffee, the caffeine, polyphenols, and other coffee molecules are fat-soluble, meaning they easily pass through the lining of the gastrointestinal tract.”

We’ve finally reached the moment of truth when it’s time to talk about your new word for the day, “urination,” which Anderson told us is the science man’s word for urination.

“Once the fluid enters the bladder, the sensors begin to notice that the bladder is filling,” Anderson said. “This sends signals to the urinary center (look, here it is) in your brainstem, which is near other centers that tell you, for example, when you are thirsty, hungry or want to vomit.”

Coffee speeds up the process because the caffeine it contains provides additional stimulation to the detrusor muscle, the smooth muscle in the bladder wall. (It remains relaxed so the bladder can store urine, and contracts when the time comes.) With your brain and bladder working together, you suddenly ask the person sitting next to you in the cafe, “Would you look at my stuff?” just a minute while I go to the bathroom?

This accelerated process is even faster if you have an overactive bladder, Anderson says, citing studies of people with the disorder. Drinking eight ounces of caffeinated water made them go to the bathroom much earlier than when they drank just eight ounces of plain water.

Another fun fact about your bladder size: That short line at the men’s room isn’t just about patriarchy. It turns out that men “can hold more fluid in the bladder and hold it longer,” Anderson said.

While everything you drink will eventually have to be eliminated, it’s the caffeine in coffee that speeds up the process. “Caffeine irritates the bladder, and when the bladder is irritated, it starts to contract.” said Dr. Rena Malik, urologist, assistant professor of surgery and director of the Division of Female Pelvic Medicine and Reconstructive Surgery at the University of Maryland School of Medicine. “This contraction gives you a sense of what we urologists call ‘urgency,’ which is a sudden urge to go to the bathroom that you can’t put off.”

Malik noted that research has shown that while caffeine does increase urges, some tolerance may develop in those who consume it in large quantities (through drinks or food). In her practice, she sees great diversity in each person’s body. “Some patients tell me that even a cup of coffee makes their morning miserable, while others can drink quite a lot and not suffer any side effects.”

Although coffee is a liquid, caffeine is a diuretic, meaning your kidneys can pull more fluid from your body than you just consumed without hydrating you at all. So, if you feel like you’re peeing more than you just drank, you’re probably right. And you need to put some plain old water in the system, stat.

The more caffeine you drink, the worse it can get. “The diuretic properties of caffeine occur at higher levels of caffeine consumption,” Anderson said. “You typically need to take more than 400 mg of caffeine for it to have a significant effect on your body’s fluid balance.” This is approximately amount of caffeine in four cups of brewed coffee, which is also the recommended daily intake.

Malik said a quick way to tell if you’re dehydrated from that coffee is to check the color of your urine. “If it’s really dark yellow, you need more fluid in your body,” she said. “If it’s almost clear, you’re drinking too much. But if your urine is lemonade yellow, your fluid levels are likely in good balance.”

“If you want to reduce how often you go to the bathroom, you don’t have to jump on caffeine,” Malik said. “You can take it slow, so if, for example, you drink two cups of coffee every morning, try drinking one cup of regular coffee and one decaf and see what happens.”

Finally, if you feel like you spend most of your life in a toilet stall, Malik advises you to see a urologist. “People might think, ‘I’ve been like this all my life,’ but you don’t have to suffer. A urologist can help you consider all your options, including lifestyle changes, medications and procedures.”