Glennon Doyle revealed she has anorexia after believing she was bulimic. An eating disorder expert said a shift in diagnosis is actually common.

• "Untamed" author Glennon Doyle said a doctor recently diagnosed her with anorexia.
• Doyle had initially been diagnosed with bulimia, and has been open about her eating disorder in books and on her podcast.

Author Glennon Doyle has been open about her experience with bulimia — but she recently revealed she may have actually been struggling with anorexia.

Doyle said on her podcast, We Can Do Hard Things, that she visited a new doctor who specialized in eating disorders after she believed she had a bulimia relapse.

After a series of blood and bone density tests and reviewing her medical history, the doctor diagnosed Doyle with anorexia.

The Untamed author described her new diagnosis as a "shift of her identity" after she had seen herself as bulimic for decades. Doyle said she did not believe her doctor at first, and had trouble speaking and eating immediately after the visit.

"Anorexia is a totally different thing," Doyle said. "It's like a different religion. It's a different identity. It's a different threat. It's a different way of thinking. So confusing."

Patients with eating disorders can experience changes in diagnosis over time

Though Doyle said on the podcast she may have actually been anorexic her whole life despite her initial diagnosis, her diagnosis may have simply changed over time, according to Kim Claudat, the director of the Adult Treatment Program at University of California San Diego's Health Eating Disorders Center for Treatment and Research. (Claudat was not involved in Doyle's diagnosis or treatment.)

Claudat told Insider many patients experience "diagnostic migration," or changes in diagnosis, because eating disorders are usually chronic conditions that persist throughout the lifetime.

Bulimia nervosa is a mental health disorder characterized by cycles of binge eating and purging through forced vomiting or taking laxatives. In her bestseller Untamed, Doyle said she had been admitted to a mental health hospital in high school where they diagnosed her with bulimia.

Anorexia nervosa, another eating disorder, is typically associated with restricting food intake, but patients with the eating disorder can binge and purge as well, Claudat said. Anorexia has the highest mortality rate of any mental health disorder, and can lead to long-term physical health conditions like anemia, osteoporosis, and heart failure.

To meet the criteria for an anorexia nervosa diagnosis, patients must have a significantly low bodyweight, Claudat said, because treatment and recovery focuses on increasing weight.

Eating disorder patients can form 'strong attachments' to their diagnosis

Claudat said many eating disorder patients like Doyle have a strong attachment to their diagnosis, because eating disorders are chronic conditions that often start during adolescence – formative years for identity-shaping.

"That's why, in treatment, we help people identify their values and build an identity outside of their disorder," Claudat added.

But clinicians and eating disorder experts try not to put too much stock into a diagnosis, since a large number of eating disorder patients do not fit neatly into the specific definitions for anorexia or bulimia. Instead, they address and treat symptoms and behaviors.

Claudat said someone with an eating disorder who is concerned about misdiagnosis or diagnostic migration should be open with their provider about all symptoms.

"I think sometimes people are misdiagnosed because they have limited insight into their eating disorder, or they may keep aspects of the eating disorder secret due to fear, guilt, and shame," Claudat said. "If you are seeking attention because you think you're struggling with an eating disorder, be as open and honest with the provider about your behaviors and symptoms as possible."