Now 28, she is in therapy and rehab, and says she's sharing her story with the hope that experts can learn to identify the addiction quickly before it's too late, reports the Daily Mail.
When Katherine's exercise habit kicked in, she also began to restrict the amount of food she was eating, which quickly spiraled into a full-blown eating disorder.
While attending Sarah Lawrence College, she received treatment for the eating disorder, but her exercise habit wasn't addressed.
"No one knew how to treat that back then," Katherine told ABC News.
Soon, the exercise started to damage her body.
Her period stropped for two years. Her feet had stress fractures and she had herniated discs in her spine.
Katherine said that her compulsive need to exercise left her with "no social life". Her personal relationships began to suffer as well.
"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."
"I wouldn't want to stay out late or do anything that would interfere with my gym schedule."
Katherine said she would "only meet someone for specific amount of time" and would get anxious if the workout had to be cut short.
In 2015, Katherine went into treatment and decided to team up with researchers from Jacksonville University and High Point University in North Carolina to bring attention to the dangers of "exercise addiction".
"People say 'Wow, I wish I was addicted to exercise', but exercise can be pathological if too much." co-author Dr Heather Hausenblas, a professor of kinesiology at Jacksonville University, told ABC News.
Exercise addiction is not officially classified as a mental health disorder, but there are recognizable signs and symptoms, both physical and psychological.
Overuse injuries, including stress fractures and tendon injuries, often occur.
Exercise addicts will push through such injuries and sacrifice relationships with family and friends, along with occupational and social responsibilities, in order to maintain their habit.
Withdrawal effects can also been seen when exercise schedules are stopped or disrupted, usually in the form of anxiety, irritability, restlessness and inability to sleep or concentrate
The condition affects between 0.3 and 0.5 percent of the general population and as many as 1.9 to 3.2 percent of those who regularly exercise, according to the researchers.
Dr Hausenblas and her colleagues say that because diagnosing exercise addiction is difficult, it should be based on a detailed conversation with the person that includes questions similar to those in diagnosing other addictions.
And the goal of treatment should not be to stop exercising completely, but to help people recognise their addictive behavior and figure out a way to incorporate workouts in healthy way.
Katherine says her treatment has taught her to be more mindful and to cut down on the time she feels is necessary to spend at the gym.
She's since written a book on her experience.
Katherine admits she still works out about 45 minutes a day, but she's careful not to push herself.
"[It's] not compulsive, overwhelming activity that rules everything," she said.
