This Is Why Your Coffee Isn't Working Anymore, and How to Do a Caffeine Tolerance Reset

If you're like us mere mortals, you start your day by stumbling straight to the coffee maker. Once upon a time, that may have given you the invincible buzz you needed to power through emails, to-do lists and a HIIT workout, but now, perhaps you find you need 2, 3 or even more cups of coffee to get the same feeling of alertness.

This isn't an unusual phenomenon, and there are actually intricate processes occurring in your body that result in this decline in caffeine power.

Here's why caffeine doesn't affect you the same way anymore, and what you can do about it.

Caffeine makes you feel bright-eyed because of how it affects substances in your body.

Because it promotes alertness, caffeine is known as a stimulant. In particular, it acts as an adenosine receptor antagonist, per the American Academy of Sleep Medicine (AASM). That means it blocks adenosine, a substance in your body that promotes sleepiness, and prevents you from falling asleep. Caffeine can also boost your reaction times, mood and mental performance.

"The adenosine receptors in your brain play a role in sleep, arousal and cognition," says Danielle Gaffen, RDN. "Caffeine temporarily blocks these receptors, creating the effect of feeling more alert, less tired and more energized."

Caffeine may block up to 50 percent of these receptors when it is repeatedly consumed throughout the day, per a November 2012 study in the ​Journal of Nuclear Medicine​​.​

However, the natural stimulant works best when you take it on an intermittent, off-and-on basis — rather than religiously every morning (understandably, easier said than done, we know).

Consuming caffeine daily makes it less effective because your body builds up a tolerance to it, per the AASM. While it can help improve your concentration and energy, the effects of caffeine will be brief if you drink large amounts daily.

"Unfortunately, by drinking caffeinated beverages regularly, the brain compensates by creating more adenosine receptors, thus allowing more adenosine molecules to bind to them," Gaffen says.

Your own biology may also affect how quickly you build up a tolerance to caffeine.

"People have different tolerances and responses to caffeine, which is partly influenced by genetics," says Mia Syn, RDN. "Consuming caffeine regularly can promote a caffeine tolerance in some people, so that the side effects from caffeine may diminish over time. Because of that, a higher amount needs to be consumed to feel its same stimulant effects."

Of course, you can't continue to gulp down additional cups of coffee until you reach your beloved state of buzzed bliss.

Up to 400 milligrams of caffeine per day appears to be safe for most healthy adults, per the Mayo Clinic. That's about the amount in 4 cups of brewed coffee.

If you consume more than that, the Mayo Clinic states you may have unpleasant (and probably familiar) side effects such as:

• Headache
• Insomnia
• Nervousness
• Irritability
• Frequent urination or inability to control urination
• Fast heartbeat
• Muscle tremors

Not much research has been done on the topic of tolerance to daily caffeine. However, researchers did track the effects of caffeine tolerance in 11 healthy active people in one January 2019 study in ​PLOS One​​.​

"By taking a break from caffeine, you're letting the adenosine receptors readjust back to a lower level, thereby making your tolerance lower and the effects of caffeine feel more powerful."

The participants ingested about 200 milligrams of caffeine for 20 consecutive days in one treatment and a placebo for 20 days in another treatment. In comparison to the placebo, caffeine significantly increased peak cycling power for the first 15 days. However, after that point, the performance-enhancing effect of caffeine lessened.

Meanwhile, frequently drinking caffeine failed to enhance mental alertness and mental performance in a March 2013 study in the journal ​Psychopharmacology​.

Cutting back on caffeine may give your body the chance to become less tolerant of it.

"By taking a break from caffeine, you're letting the adenosine receptors readjust back to a lower level, thereby making your tolerance lower and the effects of caffeine feel more powerful," Gaffen says.

However, you shouldn't stop cold turkey: Quitting caffeine abruptly when you've developed a dependence on it can cause withdrawal symptoms like headaches, tiredness, difficulty concentrating, nausea, muscle pain and irritability, per the Cleveland Clinic.

The more caffeine you consume, the worse your withdrawal symptoms will be. They might start 12 to 24 hours after your last dose of caffeine, and can last two to nine days.

• Gradually decrease your caffeine intake by keeping track of how much you're drinking, and decrease that amount slightly each day, per the Mayo Clinic.
• You can also try decaf coffee if you love the taste of java but don't want all the caffeine. Or opt for these tasty coffee alternatives.
• Try to cut out caffeinated beverages later in the day so your body gets used to less caffeine — which will lessen potential withdrawal effects.

If you love that feeling of being on your toes, that's perfectly OK! There are plenty of other ways to feel energized without relying on caffeine.

​1. Pair up protein and fiber:​ What you eat can make a big difference in your energy levels. "Pair lean protein with a fiber-rich carbohydrate to provide lasting energy," Syn says. "Some examples include low-fat yogurt with fruit, apple slices with peanut butter or carrots and string cheese."

​2. Blend up a smoothie:​ Not only will a fruity, cool drink give you a morning a pick-me-up, but the leafy greens will benefit your energy on a cellular level. "Greens contain natural nitrates that turn into nitric oxide in our body, which is a compound that opens our blood vessels, allowing more energizing oxygen and nutrients into our brain and body cells," says Dawn Jackson Blatner, RDN.

​3. Try a beetroot latte:​ Simply combine beetroot powder, unsweetened warm milk, a little cinnamon and a drizzle of maple syrup or honey. "Beets also contain high levels of energizing nitrates," Blatner says. "This tastes so much better than you'd expect, and it's a pretty pink color." If you're weaning off caffeine, you could also try a matcha latte — while matcha green tea does have some caffeine, it has much less than coffee, Blatner adds.

​4. Stay hydrated:​ Because you get about 20 percent of the water you need from food, people assigned female at birth need about 9 cups of fluid per day and people assigned male at birth need about 12.5 cups, according to the Academy of Nutrition and Dietetics. "Even being mildly dehydrated can lead to fatigue," Gaffen says. "Try drinking a glass of water or herbal tea in the morning right after you wake up."

​5. Get moving:​ Physical activity increases your heart rate and gets your blood flowing, and sending all of that extra oxygen and nutrients to your muscles can give you more energy, per the Cleveland Clinic. "Even a brisk walk or gentle movement will help to boost energy and mood," Gaffen says.