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Caffeine tolerance: Why you need more and more coffee to get a boost

If one cup of coffee or tea just isn't doing it for your anymore, here's how to cope.

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You can definitely build up a tolerance to caffeine.

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Before college, I hardly consumed caffeine in any form. I'd have a cup of coffee here and there because I liked the way it tasted. But, as a freshman in college obsessed with getting good grades, I started using coffee to help me study late at night after finishing classes and work. 

I didn't know then what I was setting myself up for. Fast-forward to college graduation and I was a certified coffee addict. I needed a 16-ounce Tervis tumbler of it to get through the day, at a minimum. 

After realizing my coffee intake increased (yet I didn't feel more alert), I tried to cut back by going to half-caffeinated coffee and then decaf. My stints never lasted long, but every time I reverted to fully caffeinated java, I felt totally jazzed -- for a few days, at least, and then the effects would wane. 

Several years after wondering why coffee seems to stop working for me, I finally decided to consult an expert on the topic. Anika Christ, registered dietitian and director of client optimization at Life Time, discusses caffeine tolerance and whether it's something to really worry about.  

Read more: Is coffee a good pre-workout?

Is caffeine tolerance a real thing? 

Yup. The human body can definitely build a tolerance to caffeine, Christ says, just like it can to many other substances. "Developing a caffeine tolerance essentially means that the stimulating effects of caffeine become less noticeable after an amount of time," Christ explains. "This is because your body becomes less responsive to the effects."

As for how to tell if you have caffeine tolerance, "I think the main inclination is if your caffeine, whether it's a supplement or coffee, isn't providing the same bump in energy as you may be used to in the past," Christ says. "Another sign is when the caffeine starts to wear off, you develop a bit of a headache."

Look out for caffeine withdrawal symptoms like extreme lethargy, persistent headaches and trouble focusing -- these are all indicators that you may have caffeine dependency.   

How caffeine works in the body

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Caffeine is structurally similar to adenosine, a molecule that makes you sleepy.

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Bear with me for a bit of brain chemistry.

Caffeine works in your body similar to the way in which many drugs, including opioids, work. Drugs work in a variety of ways, a primary way being receptor antagonists. This means that the substance you put in your body attaches to a receptor meant for a neurotransmitter. Since the drug attaches to the receptor instead of the intended neurotransmitter, it interferes with normal messaging between your brain and body.

Caffeine in particular is a central nervous system stimulant and an adenosine receptor antagonist. Adenosine is a neurotransmitter that causes drowsiness by slowing down nervous system activity. Caffeine molecules have a nearly identical structure adenosine, so when you drink coffee or other caffeinated beverages, such as energy drinks, caffeine intercepts the receptors intended for adenosine. 

It essentially fools your adenosine receptors and then does the opposite of what adenosine does: It constricts blood vessels in the brain, increases nervous system activity and signals the adrenal glands to produce epinephrine (adrenaline). It also increases dopamine signaling, which is part of the reason why your morning coffee puts you in a good mood. 

All of those physiological changes are responsible for the alertness -- and sometimes nervousness -- that occurs after you drink a cup of coffee. 

Why one cup of coffee isn't enough anymore 

Coffee doesn't just bind to adenosine receptors. It actually triggers your brain to produce more adenosine receptors, since your brain thinks all of its existing receptors are full, yet it can't identify adenosine in your system. 

So it makes more adenosine receptors, which increases the likelihood that adenosine actually goes where it's supposed to. This is your brain's attempt at maintaining balance in the face of constant caffeine consumption. 

Because you now have more adenosine receptors to fill, the same amount of caffeine won't affect you as profoundly. 

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First you only need one cup; soon you need two.

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How to avoid or fix caffeine tolerance

Avoiding caffeine tolerance is a tough task for many people, Christ says, and it's not just about flat-out reducing your intake. Quitting cold turkey doesn't work for most people.

"A key step to avoid developing a caffeine tolerance is varying your intake," she explains. "If you have a few cups of coffee on Monday, maybe have only one or half a cup on Tuesday, then none on Wednesday. Then you can go back up later in the week."

The trick, it seems, is to keep your brain on its figurative toes.

If you already feel dependent on caffeine, well, you have some work to do, Christ says. Cutting back on any substance you rely on won't be easy. Reducing or eliminating caffeine consumption can result in withdrawal-like symptoms, including fatigue, mood swings, headaches, shakes and nervousness, depending on how severe your tolerance is. 

You may want to try reducing your consumption little by little. Try half-caffeinated coffee so you can physically drink the same number of ounces, but consume less caffeine. Substituting with other beverages, such as tea, may also make the process less excruciating. You may also want to try a full-on placebo, like decaf coffee. 

If fatigue is your main problem, try these four tips for combating sleepiness sans coffee.

Definitely avoid drinking caffeine late in the day, because it'll mess with your sleep and set you up for a grueling cycle of poor sleep, which makes you want more caffeine.

Importantly, Christ says, "I want to remind people it's important to take care of yourself, so eat right, don't skip meals and get enough sleep, because if you don't, you may experience decreases in energy, which will make you want more caffeine."

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.