How Fast Do You Metabolize Caffeine?

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by Perri O. Blumberg
So many of us live for the caffeine jolt that comes with our coffee or pre-workout, but have you ever noticed that caffeine hits people differently? While one mug or shaker cup may be enough to get your engine running, someone else may need an entire thermos to perk up. That’s because people metabolize caffeine at different rates. Experts have even taken to using the terms “fast metabolizer” and “slow metabolizer” to characterize how certain individuals respond to caffeine.
It’s more than just jargon, too. In fact, it’s pretty important to know what kind of caffeine metabolizer you are. “It’s important for a variety of reasons,” says dietitian Kristin Gillespie, R.D., L.D., advisor for Exercise With Style. “First, your caffeine metabolism can impact your long-term health. And secondly, slow metabolism of caffeine can cause significant and unpleasant short-term side effects.” So, if you want to avoid undesirable effects in both the short- and long-term, knowing how you personally process caffeine is a must.
Below, some milligrams of wisdom from nutritionists on what these caffeine metabolism categories mean, how to determine which you fall into, and tips for tweaking your caffeine routine accordingly.

What Do “Fast Metabolizer” And “Slow Metabolizer” Mean?​

Here’s what this whole caffeine metabolism spectrum is all about: “‘Fast metabolizers’ refers to those that have a low sensitivity to caffeine, while ‘slow metabolizers’ have a high sensitivity,” says Gillespie. “The fast metabolizers essentially break down caffeine more efficiently than slow metabolizers, so its effects are less pronounced and shorter-lasting.”
Put another way, a fast caffeine metabolizer can consume caffeine-containing products such as coffee or energy drinks and feel the effects come and go much more quickly than slow metabolizers, explains dietitian Roxie M. Calloway, M.S., R.D. of Keto Diet Steps. “This is because they have a greater ability to break down the chemicals in those products and remove them from their system,” she says. As a result, fast metabolizers can generally drink coffee or caffeinated tea without feeling harsh jittery effects. Instead, they’re more likely to feel alert or have higher energy levels for a few hours after consumption, Calloway notes.
Read More: 5 Signs You Need A Break From Caffeine
Slow metabolizers, meanwhile are more sensitive and likely to experience unpleasant side effects as a result of caffeine staying in their system for longer.

How To Tell If You’re A “Fast” Or “Slow” Caffeine Metabolizer​

If you’re sensitive to caffeine (a.k.a. a slow metabolizer), you’ve likely known for quite some time. However, it is possible that you’re confusing caffeine sensitivity with something else, like anxiety or stomach woes, if you haven’t honed in on caffeine as the specific culprit behind symptoms.
“Knowing how you metabolize caffeine allows you to create a caffeine plan for your body,” says Calloway. When you know what kind of effects caffeine has on you and how much of it you consumed, it’s easier to avoid potential negative effects from consuming too much.”
To determine your status, ask yourself the following questions about caffeine:

• Does it give you the jitters? How long does it take for the jitters to subside?
• Does it give you heartburn or stomach upset?
• Do you have increased anxious feelings when you consume it?
• Is your sleep affected depending upon how much caffeine you consume or how late you consume it?
• Does it give you heart palpitations?

If you answered ‘yes’ to one or more of these questions, you’re likely a slow metabolizer, or more sensitive to caffeine.

What To Know If You’re A Fast Metabolizer​

“Fast metabolizers tolerate caffeine well, even in larger amounts,” shares Gillespie. “They experience increased energy and alertness for a few hours following caffeine consumption without the negative side effects slow metabolizers will experience.”
Another perk: “Fast metabolizers have also demonstrated health benefits associated with caffeine consumption, including reduced risk of high blood pressure and heart disease,” she adds.

Advice For Fast Metabolizers​

Good news for fast metabolizers: “Research has shown that consuming one to three cups of coffee daily has a cardio-protective effect in fast metabolizers,” Gillespie says. “Because they clear the caffeine more efficiently, they are able to reap the benefits of the antioxidants and polyphenols found in coffee, without dealing with the harmful effects of lingering caffeine.”
Gillespie does caution, though, that fast metabolizers are more likely to have spikes followed by dips in energy levels resulting from consuming and then clearing caffeine. “As a result, they may find themselves requiring coffee more often throughout the day to keep their energy levels up,” she notes.
In general, try drinking your coffee, tea, or other caffeinated beverages (or nibbling on that dark chocolate) earlier in the day as opposed to in the late afternoon or evening. While fast metabolizers are less likely to have trouble sleeping after consuming caffeine later in the day, it’s still best to steer clear, Gillespie says.

What To Know If You’re A Slow Metabolizer​

As Calloway defines it, a slow caffeine metabolizer is someone who has a low ability to break down the chemicals in coffee. “This means that these people can experience the jittery effects of caffeine at an earlier point in time and stay wired for longer than those with a fast caffeine metabolism,” she comments, adding that a portion of slow metabolizers experiences this as being nervous or jittery. The slower your caffeine metabolism, the more intense these side effects become.
Being a slow metabolizer doesn’t mean you have to shun caffeine altogether, but it does mean you should keep some considerations in mind when consuming it (though some slow metabolizers likely aren’t huge coffee fans because of how it makes them feel anyway).
Plus, in addition to the not-so-fun short-term side effects, slow metabolizers are also more likely to experience health issues as a result of caffeine consumption over time—quite the opposite impact fast metabolizers experience, Gillespie says. “For slow metabolizers, caffeine may increase the risk of heart disease and high blood pressure,” she highlights.

Advice For Slow Metabolizers​

Gillespie recommends slow metabolizers drink no more than one cup of a caffeinated beverage or 200 milligrams of caffeine (one or two eight-ounce cups of coffee, three shots of espresso, or four mugs of tea) per day, depending on your tolerance. However, “some may not even tolerate this much,” she adds.
Read More: 6 Ways To Conquer The Midday Slump Without Caffeine
Calloway shares three more helpful guidelines for slow metabolizers:

• Try decaffeinated coffee or coffees that are low in caffeine. This will likely make it easier to feel the effects of the caffeine later in the day.
• Drink your coffee on an empty stomach. It will allow the caffeine to be quickly absorbed and make you feel its effects sooner.
• Definitely avoid consuming caffeine later in the day, as doing so will likely affect your sleep, leading to hours spent tossing and turning instead of resting.

The Bottom Line​

Since caffeine has such a pronounced effect on your body, it’s important to incorporate it in a way that benefits your health and well-being—and to know when abstaining or cutting back is your best move. Everything from your productivity at work to your performance in the gym to your sleep quality will thank you.