When Dr. Hannah Douglass started her research, she wanted to help people who had run out of options. The 21 women in her study had been living with anorexia nervosa for an average of 11 years — more than a decade of struggling with a serious eating disorder that changes how people see their bodies and often leads to dangerously low food intake. Many had tried different treatments without long-term success. So Douglass, then a Ph.D. student at Imperial College London, decided to test something new: psilocybin, the active ingredient in magic mushrooms, combined with talk therapy.
The pilot study, published in the British Journal of Psychiatry, gave each participant three doses of oral psilocybin over six weeks inside a supportive therapeutic setting. The first dose was small — just 1 milligram, meant to feel like nothing. The other two were larger doses of 25 milligrams each. Before and after each session, participants talked with therapists to help them process what they experienced. Nobody in the study knew which dose they were taking at any given time.
The results surprised even the researchers. Two weeks after the final session, 18 out of 21 participants showed measurable improvements in their eating disorder symptoms. At three months, nearly half — 48 percent — had scores similar to someone without an eating disorder. Participants also said they felt more motivated to recover, and that motivation lasted for a full year after treatment ended.
The treatment appeared safe for most participants. The most common side effects were headache and nausea, and one woman dropped out after her second dose. There was no meaningful change in participants' BMI (a measure of body weight relative to height), though researchers noted they only tracked this for six weeks. One participant was hospitalized after suicide attempts at seven and nine months following treatment, but investigators carefully reviewed this case and determined it was not related to the psilocybin — noting that people with anorexia already face a higher-than-average risk of suicidal thoughts.
Researchers emphasized that this was a small, early-stage trial without a comparison group, meaning they cannot say for certain whether psilocybin was the cause of the improvements. Professor Robin Carhart-Harris, the study's senior author, called it a pioneering trial with promising results that justify larger, more rigorous studies. He also noted an unexpected success: the study's retention rate was excellent. In anorexia treatment, keeping people engaged over time is notoriously difficult, and this study managed to hold onto nearly everyone who started it.
For now, Douglass said more research is needed to see if these findings hold true for more people. But for a condition where existing treatments often fall short, even early signs of progress matter.