— -- Since she was in elementary school, Katherine Schreiber, 28, remembers struggling with body issues. Sometimes these feelings were so severe she felt she was "too ugly" to go to class.
Schreiber told ABC News she felt "so self-conscious, obsessed with imperfections."
As a teenager, she thought she found a solution to counteract her feelings of self-hatred: exercise.
"If I exercised, I could control that feeling," Schreiber explained. "[I] got into exercise in high school, started twice a week, then became three times a day."
With Schreiber’s exercise habit she also began to restrict the amount of food she ate, which eventually became full-blown eating disorder. In college, she finally received treatment for the eating disorder, but the treatment didn’t address her exercise habit.
"No one knew how to treat that back then," she said.
After graduation from college, she became obsessed with working out.
"I was functional on paper, worked at a magazine," she said. "[I] would go to the gym before the office, lunch break and after work. My weight was dangerously low."
She was working out so much, her body started to react. Her period stopped for two years, she had stress fractures in her feet and herniated discs in her spine. Schreiber said she was so consumed with needing to exercise that she felt she had "no social life.”
Schreiber, who is now in treatment and is a master of social work candidate at Fordham University, co-authored a review with researchers from Jacksonville University and High Point University in North Carolina to call attention to the dangers of exercise addiction.
"We wanted to bring awareness," Dr. Heather Hausenblas, a professor in the department of kinesiology at Jacksonville University and a co-author of the review, published today in The British Medical Journal, told ABC News. "People say ‘Wow, I wish I was addicted to exercise,' but exercise can be pathological if too much."
Symptoms more often associated with alcohol or substance addiction including obsession, bodily harm and withdrawal effects are also found in exercise addiction. By publishing the review, both Hausenblas and Schreiber hope both psychology experts and others can learn about the condition and ways to identify it.
Exercise addiction is not officially classified as a mental health disorder, but those diagnosed can have similar signs and symptoms. While there are only a few published studies looking at this condition, exercise addiction affects 0.3 to 0.5 percent of the general population and as many as 1.9 to 3.2 percent of those who regularly exercise, researchers said.
They outlined two types of exercise addiction: primary and secondary.
While the secondary type is seen in people with eating disorders as a way to control weight, the primary type of exercise addiction is not associated with eating disorders.
"It’s not the amount of exercise but the motivation behind it … the compulsion, the drive to do the amount of exercise," said Hausenblas. "They are doing it from a performance standpoint and not related to body-image issues."
People with the addiction can also swing from primary to secondary and back, as Schreiber did, the review says. While she originally started to control her weight and physique, she later said she felt "was addicted to the actual activity itself."
"I wouldn’t want to stay out late or do anything that would interfere with my gym schedule," Schreiber said. She would "only meet someone for specific amount of time [and] would get anxious if cut the workout short to meet someone.”
In the review, Hausenblas and her co-authors found that those diagnosed with exercise addiction may have other addictive behaviors, including shopping and internet addiction, and many have tendencies such as anxiety and impulsiveness. Men and women are equally at risk for exercise addiction, but men appear to be more affected by primary exercise addiction than women.
Certain physical activities are more associated with exercise addiction; the researchers found that up to 25 percent of runners and 30 percent of triathletes may be affected.
The symptoms of exercise addiction can be both physical and psychological. Overuse injuries are often reported including stress fractures and tendon injuries. Those affected may exercise despite these injuries and sacrifice family, social and occupational responsibilities in order to maintain their exercise habits. Withdrawal effects can also been seen when exercise schedules are stopped or disrupted, including anxiety, irritability, restlessness and inability to sleep or concentrate.
Schreiber said not only did her body suffer, but her relationships did too.
"I was unable to form or maintain close relationships," she said. "I didn’t have time to spend with friends or develop a deeper connection with my partner."
Hausenblas and her co-authors said that diagnosing exercise addiction can be difficult and should be based on a detailed conversation with the person that includes questions similar to those in diagnosing other addictions.
These questions, included in a sample questionnaire included in the review, address the amount and frequency of exercise, motivation to exercise and the effects that exercise has on overall life quality.
Most physically active people are able to control their desires to exercise and do not go through the withdrawal symptoms or negative social effects caused by their exercise routines as someone with exercise addiction does, researchers said.
Treatment of exercise addiction should be focused on addressing the addictive behavior and changing the way someone thinks about it — also called cognitive behavior therapy — researchers said. The goal is not to stop exercise completely, but to help people recognize the addictive behavior, the harms it may have their well-being and change their routines.
Schreiber began receiving treatment in 2015, that helped her be more mindful and cut down on the time she felt she had to be at the gym.
Today, Schreiber, who wrote a book about her experience before joining Hausenblas for this review, said she still works out about 45 minutes a day — but she's careful to not push herself too hard.
"[It’s] not compulsive, overwhelming activity that rules everything,” she said.
As messages and reminders become more pervasive in American culture to stay active and exercise, Schreiber’s experience highlights what can happen if working out becomes so much of a focus that takes over a person’s life.