Written by Erin Yeh
Anorexia nervosa is a mental illness characterized by severe food restrictions, self-starvation, significant weight loss, fear of gaining weight, and body dissatisfaction. Even after regaining weight, patients still experience psychological struggles, which increases the risk of relapse. It’s not enough to just reach your target weight. Although dietary interventions may raise concerns about promoting unhealthy eating patterns, the ketogenic diet may be an effective solution.
Researchers from the University of California San Diego School of Medicine conducted a pilot study to determine whether the keto diet represents an effective intervention for treating anorexia (Communications medicineDigital ID: 10.1038/s43856-026-01644-0). They also measured the feasibility and safety of the keto diet for weight maintenance.
Current anorexia treatment plans center around regaining weight through structured meal plans, but they do not address the fear of gaining weight. With emerging evidence showing the relationship between nutrition and mental health, as well as metabolic changes in the brain, it is hypothesized that what patients eat may play an important role in psychiatric disorders.
On the keto diet, the idea is to have the body break down fat through ketosis for energy. In addition to improving cell energy metabolism, ketosis therapy has been associated with decreased oxidative stress and inflammation, as well as upregulation of key neurotransmitter systems. In anorexia, self-starvation can lead to ketosis, but leads to emaciation and death. The team suggests that the keto diet — which replicates the metabolic effects of starvation without caloric deprivation — could have therapeutic benefits.
The study included 22 participants between the ages of 18 and 45 with a history of anorexia. They have been restored or slightly underweight to allow flexibility in dealing with weight fluctuations. All participants were female and most were white and non-Hispanic. There was no placebo group.
There was no target weight for participants. Instead, the team aimed to maintain weight and told participants they could not get below a BMI of 17.5. The experiment lasted over 14 weeks, and four participants dropped out during the experiment, resulting in 18 participants completing the entire experiment. Participants were also asked to complete self-assessment tools to measure various depressive and eating disorder symptoms: Eating Disorder Examination Questionnaire (EDE-Q), Eating Disorder Inventory-3 (EDI-3), Eating Disorder Clinical Impairment Inventory, Beck Depression Inventory-2, Spielberger Trait Anxiety Inventory, and Temperament and Personality Inventory (TCI).
The diet consists of three meals and two snacks daily, and consists of 70% fat, 20% protein, and 10% carbohydrates. Food was provided through a ketogenic meal delivery service, but participants were allowed to prepare their own meals with the assistance of a dietitian. To monitor nutritional ketosis, participants underwent daily blood draws for the first two weeks and then once a week thereafter. Participants provided weekly self-assessments on anorexia symptoms, mood, anxiety, suicidal thoughts, ketone levels, and weight. They also received up to three hours of counseling support. Three months into the study, participants answered questionnaires, provided their weights, and followed up with the researchers to provide more qualitative feedback and confirm whether they would continue on the keto diet.
Potential of the Keto Diet
The research team reported that there was a significant difference between participants who completed the experiment and those who did not. 72% of completers reached the recovery range for eating disorder symptoms, according to their global EDE-Q scores. Participants with lower Novelty Seeking (TCI) scores and higher Low Self-Esteem (EDI-3) scores did not fall within the normal range, indicating poor improvement in anorexia. The completers group had lower novelty seeking and higher harm avoidance, depression, and lower self-esteem scores. At the 3-month follow-up, 39% of participants reported that they continued the keto diet while 61% did not.
Some participants initially reported significant anxiety and required significant training to maintain adequate intake, but their confidence in the nutritional intervention improved as the study progressed. By the end of the study, all participants showed improvement in depression scores. Post hoc analysis also showed that low self-esteem was associated with a higher global EDE-Q score.
In the field of eating disorders, there is always concern about dietary interventions that trigger symptoms or promote unhealthy eating habits. With the keto diet often portrayed as a weight-loss diet, researchers looked into the possibility of participants relapsing. Fortunately, those concerns were not found in the results. The keto diet was generally well tolerated and highly effective in reducing symptoms of depression and eating disorder, except in individuals who demonstrated low self-esteem. Furthermore, anecdotal comments made by supplementers indicated increased confidence and surprise that the keto diet provided levels of recovery they had never experienced before.
Another concern was whether the keto diet would increase fear of eating carbohydrates. However, none of the participants reported being afraid of carbohydrates. Conversely, participants felt “sluggish” when reincorporating carbohydrates.
Other limitations to consider are the lack of direct supervision of participants eating their meals. They were only asked to send photos of their meals to the research team. Therefore, the possibility that participants may restrict food intake should be considered. The study also did not take into account expectation bias, placebo effects, changes in medications, ongoing psychotherapy, and eating behaviors. There were also no laboratories before or after the intervention to determine the adequacy of nutrition.
In addition, six participants were out of ketosis, which may have affected the results. It remains uncertain why biomarkers of ketosis are associated with disordered eating and depression severity. The team encourages further research to fully confirm the effectiveness of the keto diet.
The EDE-Q was also modified for a weekly assessment schedule, which may introduce uncertainty in how results compare to other studies. Finally, the small sample size must be considered. Although the team examined factors such as use of counseling services, meal delivery, meal preparation methods, and nutritional supplements such as MCT oil and carnitine, the small sample size could influence any conclusions reached and should be interpreted with caution.
Despite its limitations, the keto diet shows promise as an effective treatment for anorexia patients. The team encourages further research, such as a controlled study to compare the keto diet with other interventions, including the Mediterranean diet, which have been previously tested in a different population. There is currently an extension of the current study that is recruiting patients nationwide.
