Only one in five Americans gets regular physical activity, so it’s hard to imagine there can be such a thing as exercising too much. But for some people, what starts as working out to get in shape or lose weight can escalate into an unhealthy need to exercise at all costs.

Experts say exercise addiction can be as serious as an addiction to gambling, driving people to go for 2 a.m. runs on dark, ice-coated roads, for example. It leads others to sign up for multiple gym memberships — a strategy that one patient of Florida psychologist Heather A. Hausenblas, PhD, used to hide how much he was exercising from his gym buddies.

Exercise addiction afflicts 3 to 5 percent of the population, research shows. Among triathletes, the prevalence of exercise addiction is estimated to be upward of 50 percent, according to a study published in the journal Eating Disorders. Another study found 25 percent of runners studied showed signs of exercise addiction.

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What exercise addiction looks like

It’s not always easy for someone who develops an exercise addiction to realize their healthy behavior has slipped into the realm of unhealthy. “They start off doing something for their health, and it begins to control them instead,” explains Michael Sachs, PhD, a sports psychologist and professor of kinesiology at Temple University in Philadelphia.

“They feel terrible, physically and psychologically, if they miss doing it, ” Sachs adds. For people who crave exercise, abruptly stopping can lead to depression, intense anxiety, hopelessness and irritability, according to other researchers.

For people who enjoy exercise, It's easy to see how seductive it can be. “It wards off tension, dampens the impact of stress and kicks off that runner's high,” says Katherine Schreiber, who co-wrote a book about her own experience with psychologist Hausenblas, “The Truth about Exercise Addiction: Understanding the Dark Side of Thinspiration.” But as with other addictive activities, it takes more and more exercise to achieve that bliss.

As her exercise addiction began to take over her life, Schreiber says she ignored aches and injuries because “taking a day off from exercise was no longer an option.” Even during her recovery, she says, “I found myself suddenly compelled to the gym for hours in order to feel better about myself, forget all my worries and get validation from perfecting my body at all costs — including ignoring travel, friends, loved ones and work.”

Schreiber also was dealing with anorexia, which is common among compulsive exercisers. Anorexia occurs as a “secondary addiction” in nearly half of all exercise addiction cases, according to Hausenblas, who specializes in the psychological effects of health behaviors at the University of Jacksonville.

Because it can be tricky to distinguish exercise addiction from a normal devotion or need to work out (training for a marathon, for example), Hausenblas co-designed an exercise dependence assessment to help identify the problem. The assessment looks at everything from how much time a person spends exercising to her “lack of control,” or ability to stop exercising.

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Kicking the too-much-exercise habit

The road to recovery has been tough for Schreiber. “I've had fundamental insecurities I’ve dealt with my whole life, and lots of anxiety,” she said. “What helped me the most was working with a therapist to get in touch with what was driving it, and slowly finding other ways to get my needs met.”

If you suspect you may be addicted to exercise, here are some steps to take.

Get in touch with a therapist or counselor. "Teaching people about being in control of exercise rather than being controlled by exercise may be just what is needed,” says sports psychologist Sachs. A therapist also may help buffer you from cultural pressure to look thin.

Consider cognitive behavioral therapy (CBT). Working with a CBT-trained therapist, you can identify where the negative feelings fueling the addictive behavior come from and come up with ways to stop those thoughts.

Engage in exercise “reprogramming.” You may be able to work with a trainer experienced in eating disorders “to relearn how to exercise in a way that is less about self-punishment and more about feeling food in one’s skin,” says Schreiber. Some programs have combined this approach with meditation, mindfulness practice and other steps to reduce stress.

Fill part of your exercise time with a shared activity. “We want people to exercise, and it is better not to go cold turkey with anything, so we try activity substitution,” says Sachs. “It is especially valuable if it’s with a loved one or friend. If someone runs three hours a day, for example, I’ll try and get them to go bowling or walk with a spouse or friend for half of that time every day.”

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Kathryn Olney is a freelance writer and editor who has served as a reporter and editor for California, San Francisco and Mother Jones magazines.