Here’s How to Undo a Caffeine Tolerance

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Photo: Vintage Images

I live in a house divided. I consume coffee (“the planet’s most perfect, most life-giving beverage,” as my colleague Melissa Dahl has rightly called it) like oxygen; my boyfriend, meanwhile, not-that-jokingly calls it the devil’s juice and clings to his low-caffeine green tea. This is a rift that is bigger than mere beverage preference. Claiming life is better without caffeine feels akin to describing puppies as Satan’s minions, or saying you are averse to sunshine and laughter — a worldview so baffling as to be nearly incomprehensible.

To be fair, though, I can grant that there may be a bit of a Stockholm-syndrome thing going on. Coffee, after all, can be a cruel mistress: The more you have it, the less it works. And caffeine tolerance kicks in fast; in one study, subjects who otherwise normally abstained from caffeine became desensitized to its effects in just one to four days. There’s a way to reset your tolerance — but be forewarned, it is not fun. And it means you’re going to have to learn some uncomfortable truths about your favorite beverage.

How Caffeine Tolerance Works

Caffeine has a similar chemical structure to adenosine, a substance that causes you to feel tired (adenosine naturally builds up in the body over the course of the day and then dissipates during sleep). When you ingest caffeine, the molecules bind to the receptors in the brain normally used by adenosine, meaning all that sleepiness-inducing stuff doesn’t have a chance to work; hence the wakefulness you feel after chugging a cup of coffee. Caffeine also causes an uptick in adrenaline, the hormone that makes you feel more alert, and dopamine, which plays a role in helping you feel happy.

Over time, your brain will start spouting more adenosine receptors in an effort to make up for what it’s missing — meaning that you’ll need to consume more caffeine to keep the sleepiness at bay, and you’ll feel increasingly worse when you don’t get it. To a point, at least.

Finding Your Coffee Sweet Spot

Eventually (thankfully) this process tends to level off, explains Murray Carpenter, author of Caffeinated: How Our Daily Habit Helps, Hurts, and Hooks Us. “Researchers call it a partial tolerance. You’re not just going up and up and up” in the amount of caffeine you need to consume, he says. “Usually, people will develop a tolerance to caffeine, but they’ll hit a point where they [find] their optimal dose with their tolerance.”

“Your body sort of finds it,” he adds. In one experiment, Roland Griffiths, a drug researcher at Johns Hopkins, gave his subjects access to unlimited coffee of varying strengths and caffeine levels and observed how they spaced out their consumption. “If you gave them weak coffee they’d drink more, and if you gave them strong coffee they’d drink less,” Carpenter says. “It really seems to be people figuring out how much caffeine their body wanted and then dosing themselves with it.”

And the amount the body wants can vary widely from person to person. Caffeine has a half-life of four to six hours (meaning your body can process half of what you’ve consumed in that amount of time), but there are still biological and lifestyle factors that can turn one person’s pleasant morning wake-up into another person’s recipe for shaky hands. Genetics and natural metabolism speed can influence how quickly you proces caffeine. So can sex; men tend to feel the effects more strongly than women.

More temporary factors also play a role. Over the course of a lifetime, “your tolerance will probably change depending on a number of things,” Carpenter says. “Weight is the most obvious one” — fluctuations up or down may mean it takes more or less caffeine to get you going. Certain antibiotics can make it more difficult to break down caffeine, and the process can take twice as long for women on hormonal birth control, as the Pill inhibits the production of certain enzymes that help caffeine to clear the body. Smokers, on the other hand, metabolize it twice as fast.

The Terrible But Effective Way to Reset Your Tolerance

Let’s say, hypothetically, that your current tolerance is a little too high for your taste. Maybe it now takes five cups of coffee for you to feel awake in the morning; maybe you don’t like how you can guzzle the stuff and still nod off right afterward. Maybe you just don’t want to be dependent on caffeine at all. Whatever the reason, getting down to a more comfortable level will require you to confront one of the harshest realities of caffeine: To make it work for you again, you have to quit it. And to quit it, you’re going to have to suffer.

The only way to undo a tolerance, unfortunately, is to cut back on the caffeine consumption for a while, either by slowly tapering off over several weeks or by going cold turkey. For the former, coffee researcher Joseph Rivera, the founder of Coffee Chemistry, suggests reducing your intake by half for a few days, then halving that for a few more days, and so on. “After about a week you should be pretty much back to how you were without drinking caffeine,” he says.

But if you’re the impatient type who wants to get to zero straight out of the gate, the so-called “washout period,” the time it takes for your body to reset itself, is also around a week — and oh, what a week it is. The DSM-5, released in 2013, controversially included caffeine withdrawal as a mental disorder; whether or not it deserves the label, though, the symptoms are very real: lethargy, focus issues, irritability.

And, of course, those headaches. “When you take caffeine, it constricts your blood vessels. That’s why a lot of times, when you don’t take it, the vessels relax and they create a pressure in your brain,” Rivera explains. “They stretch out, they press up against the nerve, and that’s what creates the headache.”

Assuming You Survive That, Here’s What to Do Next

If you’ve managed to make it through all that — well, first of all, power to you. And second, now is a time to proceed carefully. To avoid shooting back to your former tolerance all at once, try starting with small amounts of caffeine each day. “The first trick is to figure out what your daily dose is,” Carpenter says — the amount of caffeine where you plateau — and then slowly work your way back up to it. Along the way, those smaller doses should pack a punch in a way they didn’t before.

The tricky part, though: “It’s kind of hard to moderate your consumption if you’re a coffee drinker because it’s hard to get a small dose,” he says. A 12-ounce can of Red Bull contains 111 milligrams; a tall Starbucks coffee, also 12 ounces, clocks in at 260 milligrams. (The Mayo Clinic, for reference, says that around 400 milligrams of caffeine per day is safe for healthy adults, defining “heavy” use as anything more than 500 to 600 milligrams per day.) With coffee made at home, meanwhile, it can be hard to know just how much caffeine you’re getting.

If you’re trying to slowly reintroduce caffeine to your body, then, Carpenter recommends using soda — a 12-ounce can of Coke has around 35 milligrams, or 47 if it’s diet. “It’s a fun experiment that more people should try. If you’re a heavier caffeine user, I think it gives you a greater respect for the drug,” Carpenter says. “If you haven’t had any caffeine for a while, 35 milligrams can feel pretty good.” It’s a lot of work just to get to a point where you can feel that sweet, sweet buzz again, but life is nothing if not an endless roller coaster of waxing and waning pleasures — a fact the coffee addicts, much more than the green-tea devotees, confront each and every morning with the first cup.