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Your Body on Caffeine

Need a quick boost? What you pick up when you’re looking for a pick-me-up matters.

September 2022
Aabye-Gayle D. Francis-Favilla

Back to school means happy things like reconnecting with friends and catching up on summer gossip. One less fun thing? Going back to waking up early and getting out the door fast. You might be tempted to reach for your favorite caffeinated beverage (extra large, please) to jump-start your day. But do you really know what all that caffeine is doing to you? While a little bit of caffeine is not terrible, your body can become dependent on it. And using too much of it too often can lead to long-term health problems and trouble sleeping. In fact, studies have shown that teens are especially vulnerable to some of the issues associated with caffeine consumption, such as dehydration, anxiety, and (gross-out alert) diarrhea. So before you reach for that soda, latte, or energy drink, read on to find out about the effects of caffeine on your body, mind, and mood. 

HOW YOUR CUP STACKS UP

Experts say teens shouldn’t consume more than 100 mg of caffeine a day. To make sure you’re under the limit, check out the caffeine content in these popular drinks:

  • Small cup of coffee (8 oz.) 95–165 mg
  • One shot of espresso (1 oz.) 47–64 mg
  • Small black tea (8 oz.) 25–48 mg
  • Small green tea (8 oz.) 25–29 mg
  • Can of Monster Energy (16 oz.) 160 mg
  • Can of Red Bull (8.4 oz.) 80 mg
  • Can of Mountain Dew (12 oz.) 54 mg
  • Can of Coca-Cola (12 oz.) 34 mg
  • Can of Diet Coke (12 oz.) 46 mg

Note: The amount of caffeine in coffee and tea is affected by how it was brewed and the type of beans or leaves used.

Brain

That feeling of alertness associated with caffeine is caused by caffeine blocking your brain’s receptors for adenosine, a chemical that makes you feel tired. Too much caffeine can cause headaches, confusion, and even hallucinations and convulsions. 

Bones

Caffeine prevents your body from metabolizing and absorbing calcium—an essential building block of strong bones. This may put you at risk for a disease called osteoporosis, which makes your bones more vulnerable to breaks as you age.

Mood

If you consume caffeine regularly, your body will begin to depend on it. You might feel angry, depressed, or irritable if you stop consuming it. Caffeine can also intensify the symptoms of nervousness and anxiety.

Heart

Got the jitters? Caffeine can accelerate your heartbeat. Very large amounts can cause an irregular heartbeat or even cardiac arrest, where your heart stops beating altogether.

Stomach

Because caffeine increases the volume of acid in your stomach, drinking caffeinated beverages can cause an upset stomach. Too much caffeine can make you feel nauseated or cause you to throw up.

Got the Facts About Your Buzz?

Test your caffeine smarts. 

TRUE OR FALSE? Caffeine can help someone sober up. 

FALSE! Drinking coffee or other caffeinated drinks won’t affect the amount of time it takes the body to process alcohol. 

TRUE OR FALSE? Decaffeinated coffee doesn’t have any caffeine in it.

FALSE! Even decaffeinated coffee contains a very small amount of caffeine.

TRUE OR FALSE? Many foods contain caffeine. 

TRUE! Most coffee-flavored foods, like coffee yogurt, ice cream, and candy, contain caffeine. Chocolate and chocolate-based foods have caffeine, as do many types of energy bars and gels. 
Take the quiz again

SIP ON THIS

Worried about missing caffeinated beverages? Try these swaps:

Instead of a morning coffee: A hot herbal tea with honey will help you feel alert without causing jitters. 

Instead of a soda with lunch: Flavored sparkling water will keep you hydrated. 

Instead of an energy drink while you do homework: Chocolate milk (which has a small amount of caffeine) provides protein and energy to power your study sesh. 

Personal Health
Nutrition
metabolizing

verb

to use chemical processes in the body to turn food into energy, new growth, and waste products
dehydration

noun

the loss or removal of water from something
consumption

noun

the using up of a resource

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