Does Caffeine Actually Boost Your Metabolism?

Megan Meyer, PhD
by Megan Meyer, PhD
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Does Caffeine Actually Boost Your Metabolism?

I am a creature of habit. When my alarm goes off, I get out of bed (after at least one snooze sesh) and head out the door for my morning workout. What gets me through those early morning workouts? The promise of a hot cup of joe when I get back home. It’s part of my daily ritual that starts at home and trickles into my morning work routine. Whether it’s a cup of black coffee, a soy latte or a fancy cup of French press, I am a coffee lover through and through. Not only is coffee a delicious start to my mornings, but it also give my day a jump-start — all thanks to the magical molecule known as caffeine.

Caffeine is found naturally in the leaves, seeds and/or fruits of more than 60 plants, and it is one of the most studied food ingredients. Since its in widely prevalent foods like coffee, chocolate, tea and soda, you can probably imagine that the average American consumes at least some amount of caffeine each day. In fact, a recent study found that the average American’s caffeine intake hovers around 165 milligrams per day.

Is there such thing as too much caffeine?

Just like most things, there is a limit to how much caffeine you should consume each day. The Food and Drug Administration has found that up to 400 milligrams of caffeine per day is not linked to negative health effects in adults.

What does 400 milligrams of caffeine look like?

Sometimes it can get confusing how much caffeine we can safely include in our diet, so see the table below to give you a sense of how many ounces it takes to reach the 400 milligram limit.

400 milligrams of caffeine equals approximately:
8 (8-ounce) cups of black tea
4 (8-ounce) cups of coffee
2.5 (16-ounce) energy drinks
8 (12-ounce) diet sodas

Can caffeine impact my weight?

As it turns out, there is a good bit of evidence that shows that caffeine helps with weight management by boosting your metabolism.

Before we dive into the science, let’s quickly go over basic human metabolism. Your metabolism is what keeps your body going. It includes every single chemical reaction that occurs to keep your body functioning, including replicating your cells, making hormones, breaking down food and producing energy for the body. At rest, your metabolism is called your basal metabolic rate, which is your baseline metabolism needed to support your body’s basic functions. The BMR takes your height, weight and age into account. While you can burn additional calories through exercise, your BMR usually accounts for the majority of calories burned throughout the day.

Decades of scientific research have investigated the impact of caffeine on metabolism and weight management. This comprehensive study involving a series of four trials found that both caffeine and coffee stimulated the metabolic rate in healthy and overweight participants. Interestingly, these findings were linked to greater oxidation (think: “breakdown”) of fat in healthy participants.

Similarly, additional research has shown that 100 milligrams of caffeine  increased BMR by 3-4%. Breaking this down into real-world numbers, if your daily calorie needs hover around 2,000 calories, then ingesting 100 milligrams of caffeine may increase your daily calorie needs by 60–80 calories. Even though I do not need another reason to love my daily caffeine habit, I can always get behind a food or drink that adds to my calorie budget rather than takes away from it.

Do caffeine-containing beverages such as coffee improve other health outcomes?

Yes! In fact, this was a question that the Scientific Report of the 2015 Dietary Guidelines Advisory Committee investigated. This report found strong observational evidence that moderate coffee consumption (up to 400 milligrams caffeine per day) is not associated with increased risk of chronic disease such as cardiovascular disease, cancer and premature death. So it seems that your daily coffee habit can pay off in more ways than just affecting your waistline.

Final caffeinated thoughts

While coffee does have perky benefits, try to cap caffeine at 400 milligrams per day. And with that, I’m off to brew another cup of joe!

About the Author

Megan Meyer, PhD
Megan Meyer, PhD

Megan is a lover of all things science, food, and fitness. A scientist by training (go Tar Heels!), Dr. Meyer has found that being able to communicate the science is just as important as understanding the science. Dr. Meyer has a BS in Biology from Loyola University Maryland as well as a PhD in Microbiology and Immunology from the University of North Carolina at Chapel Hill and is a regular contributor to sites like US News & World Report and The Huffington Post. In her spare time, she enjoys whipping up fun recipes in the kitchen, exploring new trails, and spending quality time with loved ones. You can follow her on Twitter.

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