If You Want to Burn More Calories During Your Workout, Try This Delicious, Science-Backed Secret.

Your morning cup of coffee may be the secret to hitting your next PR.

The right shoes. A good stretch. A motivating playlist or instructor to push you to do one.more.rep.

These tools are tried-and-true workout teammates. But might there be another unheralded star lurking in your pantry?

Coffee drinkers, whether you know it or not, your pre-workout cup of Joe may be fueling your workout. In a comprehensive 2021 review and position stand, the International Society of Sports Nutrition (ISSN) pointed to evidence that caffeine supplementation can give you a boost during long, aerobic workouts and brief high-intensity activities.

"Small-to-moderate caffeine ingestion can support aerobic endurance, muscular endurance, strength, power, mental acuity and reaction time," says Dr. Brittany Masteller, a research scientist at Orangetheory Fitness.

But it's not a runaway winner for everyone.

"There are many factors that can influence how much of an impact caffeine can have on an individual," says Kendra Weekley, RD, a registered dietitian with Cleveland Clinic’s Center for Human Nutrition who holds a master's degree in exercise science.

Below, experts spilled the beans on caffeine use for exercise performance.

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Why Does Caffeine Give Some People Athletic Performance Boosts?

Amargo Couture, RD, a registered dietician at Northwell Health's Staten Island University Hospital, notes that caffeine has ergogenic effects, meaning it can aid in physical performance and recovery. 

"Caffeine binds to adenosine receptors which subsequently reduces the rate of perceived exertion you are putting forth during exercise, also known as RPE," Couture says. "Caffeine can also stimulate the central nervous system within our bodies, which can reduce the sensation of fatigue and pain."

Less pain, more gain isn't just a cliche in this case—it's physiology.

"If someone is feeling less pain...it can lead to increased intensity, volume or duration," Weekley says.

How Much of an Added Burn Can You Expect from Caffeine?

Experts were hesitant to give any hard-and-fast numbers on the additional calories you can expect to burn. Ditto for how much faster or stronger a pre-workout caffeine jolt would provide you.

Couture points to 2018 research that suggests several factors can affect how the body metabolizes caffeine. These factors include:

• Age

• Sex and hormones

• Liver disease

• Obesity

• Smoking

• Diet

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Tolerance can also play a role.

"Caffeine may also affect every person differently depending on how much caffeine you consume at baseline due to tolerance," Couture says. "If your body is used to a very high amount of caffeine at baseline, you may need to consume an even higher amount to have the same effect as someone who does not consume any caffeine."

The performance boost is similar between elite athletes—people chasing down Usian Bolt and Shalane Flanagan status—and the couch-to-5K types.

"Caffeine can be important for both elite athletes and weekend warriors/recreational athletes," Weekley says.

Older research from 2008 indicated that well-trained athletes shaved 11 seconds off their 5K times, while recreational Jogger Joes' times improved by 12 ticks.

In professional racing, 11 seconds can be the difference between prize money and walking away with nothing. Weekley says 12-second differences may not have the same appeal to recreational runners. But if that 12-second difference fuels your motivation to keep moving, consider it a win.

How To Use Caffeine To Boost Workout Performance

Weekley agrees with the 2021 review—consuming caffeine about 30 to 60 minutes before a workout will benefit you the most.

The dosage recommendations vary, however. One study of well-trained endurance athletes (who withdrew from caffeine for 48 hours before each test) suggested 1.4 to 2.7 milligrams per pound of body mass. A recent study indicated that about 200 milligrams of caffeine could enhance exercise performance.

"It may take some experimenting to find the right does for you," Weekley says. "There are many factors that can vary intake and its effectiveness from person to person."

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Caffeine can dehydrate, but small doses shouldn't be why you're parched during a workout.

"When consuming caffeine within the recommended ranges of caffeine intake, there are no known negative impacts to hydration status," Masteller says.

But it's always a good idea to have a water bottle on hand when engaging in physical activity.

Masteller also advises pregnant people to consult with their doctors. The American College of Gynecologists typically recommends pregnant people limit caffeine consumption to 200 milligrams per day.

Cons of Using Caffeine Before Working Out

Caffeine has its share of benefits, but everyone must still weigh the pros and cons.

"Since caffeine works closely with functions in the central nervous system, there can be some potentially negative side effects from too much, too late and too frequent consumption of caffeine," Weekley explains.

These drawbacks include:

• Increased anxiety

• Over-stimulation, which affects sleep, mainly if consumed too close to bedtime

• Headaches

• Increased heart rate

• Heart palpitations

Related: How Bad Is It Really to Sleep By Your Phone?

If you feel you need a timeout from caffeine, Weekley suggests weaning slowly to avoid withdrawal symptoms like headaches and irritability.

"It is OK to wean slowly and decrease your consumption a little at a time, day by day until you hit your goals," Weekley says.

Next up: 31 Different Kinds of Coffee Drinks, Explained

Sources

• Dr. Brittany Masteller, a research scientist at Orangetheory Fitness

• Kendra Weekley, RD, a registered dietitian with Cleveland Clinic’s Center for Human Nutrition

• Amargo Couture, RD, a registered dietician at Northwell Health's Staten Island University Hospital