Yes, Caffeine Withdrawal Is a Real Thing

January 15, 2015 8:00 AM EST

Ever had a time when you really needed a cup of coffee? Some days, the urge can be so strong that everything seems off until you have a hot cup of Joe in your hands.

Well, you’re not alone. Even pro athletes like Serena Williams find it hard to fight the siren call of caffeine. The tennis star made her love for coffee known during a recent match at the Hopman Cup in Perth, Western Australia.

HEALTH.COM: 12 Surprising Sources of Caffeine

Despite being the World No. 1 in women’s singles, Williams wasn’t doing too hot in her match representing the U.S. She dropped the first set 0-6 to Italy’s Flavia Pennetta.

Williams asked an official if she could order an espresso during the break between sets, SI.com reports. The request seemed silly, even to the pro herself, but the quick pick-me-up turned out to be a major game-changer.

Williams went on to dominate the next two sets 6-3 and 6-0, winning the match for the U.S. The athlete blamed a combination of jet lag and missing out on a cup of coffee as the reason for her slow start.

According to HopmanCup.com, Williams told reporters, “I am a coffee drinker. I didn’t have mine this morning and I was just feeling it, so I just had to get some coffee into me.”

HEALTH.COM: The Best Foods to Eat for Breakfast

Props to Williams for pulling off a win, but it does make you wonder just how much people really need their coffee.

“Caffeine withdrawal isn’t necessarily about addiction—it’s really more about your body adapting to having caffeine in your system, then reacting when the substance isn’t there,” says Health‘s contributing nutrition editor Cynthia Sass, MPH, RD. So if you’ve been a life-long coffee drinker, skipping your regular cup could bring on symptoms like headaches, fatigue, decreased alertness, and mood changes, she says.

“It’s more likely to happen if you [regularly] consume 500 milligrams of caffeine or more,” Sass says. “But it can happen with less if caffeine has been a daily habit.” Keep in mind 8 ounces of brewed coffee can have up to 200 milligrams of caffeine, Sass adds, while 1 ounce of Williams’ drink, the espresso, is on the lighter side with up to 75 milligrams.

See the 10 Healthiest Cities to Live in America

Honolulu, Hawaii Best Place for Lifelong Health The heavenly climate helps, but the key to well-being here also includes enviable health care and a rich cultural tradition of looking out for one another.Colin Anderson—Blend Images/Corbis

San Francisco, California — San Francisco Bay Area, Calif. Best Place for Eating Right. The "farm to table" movement began here. The region's bounty of produce and year-round growing season make eating healthy—and local—a natural.Getty Images

Burlington, Vermont — **Burlington, Vt.** *Best Place for Raising Healthy Kids* This New England city offers great schools, excellent pediatric care, loads of culture and limitless options for healthy outdoor fun all year long.Matt Hogan/www.mphoganphoto.com

**Silicon Valley, Calif.** *Best Place for Workplace Wellness* With treadmill desks, meetings on bikes, time off for creativity, and gobs of organic food, tech titans are reinventing how to stay healthy on the job.Jim Wilson—The New York Times/Redux

Minneapolis, Minnesota — **Minneapolis-St. Paul, Minn.** *Best Place for Aging Well* Yes, it can be cold. But with a plethora of stimulating activities and a robust web of support, the Twin Cities prove that growing old doesn't mean slowing down.Getty Images

Boulder, Colorado — **Denver and Boulder, Colo.** *Best Place for Keeping Fit* The urge to get outside and get moving is contagious in these Rocky Mountain cities, where physical challenge is built into the landscape.Celin Serbo—Aurora Photos/Corbis

**Plano, Texas** *Best Place for Staying Safe* Once a rural outpost, this booming, diverse city has kept its small-town vibe, thanks in part to a police force and community that knows how to work together.Misty Keasler—Redux for TIME

Portland, Oregon — **Portland, Ore.** Best Place for a Healthy Environment Small, walkable neighborhoods, 300 miles of bike paths, and urban policies that foster active living and sustainability make for one clean, green city.Getty Images

Boston, Massachusetts — **Boston, Mass.** *Best Place for Health Care* This history-rich city is home to some of the nation's most advanced medical institutions and policies that help ensure that quality care is available to all.K.C. Cohen—Courtesy of Boston Children's Hospital

Provo, Utah — **Provo and Orem, Utah** *Best Place for Spiritual Well-Being* A stunning Rocky Mountain backdrop and a tight-knit population that lives its faith contribute not only to this region's serenity but also to lower rates of disease.Getty Images

HEALTH.COM: How to Burn Calories at Breakfast

That said, there are upsides to making coffee part of your routine, especially for athletes like Williams.

“Caffeine may help boost athletic performance by increasing muscle strength and physical endurance while decreasing feelings of fatigue,” says Marisa Moore, RD, a spokesperson for the Academy of Nutrition and Dietetics. “Having caffeine during activity may give that second wind.”

Before big athletic events, it’s important to stick to what’s worked during your training routine, Moore says. If that means having a cup of coffee, then by all means do it.

HEALTH.COM: Best Superfoods for Weight Loss

Just enjoy caffeine in moderation—Sass says the recommendation for enhancing athletic performance is up to 6 milligrams per kilogram of body weight, which is about 400 milligrams per day for a 150-pound woman. And don’t use the beverage as a quick fix for fatigue when other issues like stress or diet are to blame.

“The real keys are listening to your body, and being honest with yourself about why you’re reaching for a cup of coffee (or two),” she says.

This article originally appeared on Health.com.

See the 10 Healthiest Cities to Live in America

More Must-Reads from TIME