This study will investigate the effects of therapeutic ketogenic diet (TKD) on eating behavior including drive to restrict, body dissatisfaction, mood and anxiety in individuals with anorexia nervosa who have been weight normalized (body mass index of 17.5 or greater) but continue to struggle with eating disorder behaviors including a high drive for thinness and body dissatisfaction.

The Underweight Anorexia Nervosa (AN) Sub-Study will investigate the effects of TKD on eating behavior including drive to restrict, body dissatisfaction, mood and anxiety in individuals with anorexia nervosa who are currently underweight (body mass index between 16.0 and 17.49) and continue to struggle with eating disorder behaviors including a high drive for thinness and body dissatisfaction.

The Bulimia Nervosa Pilot will will investigate the effects of TKD on eating behavior including drive to binge and purge, body dissatisfaction, mood and anxiety in individuals with bulimia nervosa.

For this 14-week study, the investigator will recruit twenty individuals with anorexia nervosa who have been weight normalized but continue to have high impairment from the illness with a high (2 standard deviations above average) drive for thinness and body dissatisfaction and a high drive for food restriction and thus are at high risk for full relapse. Study participants will be carefully assessed and oriented to the ketogenic diet according to the procedures in our small previous trial (Calabrese, et al., 2022). The study will be conducted in a university medical environment, showing feasibility and safety in a typical medical setting. A commercial supplier will provide the ketogenic diet. After ketosis induction over two weeks, study participants will be assessed weekly for ketosis and mood, anxiety, and eating disorder symptoms.

For the BN Pillot study we will also complete a small pilot in 5 individuals with bulimia nervosa.

For the Underweight Anorexia Nervosa (AN) Sub-Study we will also recruit 30 individuals with anorexia nervosa who are mild to moderately underweight and have a body mass index of between 16.0 to 17.49.

Primary Objective 1 is to test the effects of ketogenic diet in individuals with anorexia nervosa who are weight recovered but continue to suffer severely from drive for thinness and are at very high relapse risk. Participants will be evaluated for tolerability of the study and weight trajectory. Primary Objective 2 is to assess improvement in AN symptoms and behaviors in relation to the ketogenic diet over a 12-week course. Participants will be assessed for specific symptoms such as drive for thinness and body dissatisfaction, fear of eating and weight gain. Primary Objective 3 is to assess the underlying genetic basis for the treatment effect of the ketogenic diet.

Bulimia Nervosa Pilot Objective 1: To test the effects of ketogenic diet in individuals with bulimia nervosa.

Bulimia Nervosa Pilot Objective 2: To assess improvement in BN symptoms and behaviors in relation to the ketogenic diet over a 2-week induction period followed by a 12-week course of the intervention. We expect especially a reduction in binge eating episodes and associated purging episodes in response to the treatment and in addition to improvement of the cognitive emotional symptoms.

Underweight AN Sub-Study Objective 1: To test the effects of ketogenic diet in individuals with anorexia nervosa who are currently mildly underweight and assess how the intervention impacts weight normalization in this population.

Underweight AN Sub-Study Objective 2: To assess improvement in AN symptoms and behaviors in relation to the ketogenic diet over a 2-week induction period followed by a 12-week course of the intervention.

Underweight AN Sub-Study Objective 3: To assess the underlying genetic basis for the treatment effect of the ketogenic diet.

Weight-Recovered AN Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Persons, aged 18 to 45 years
4. History of anorexia nervosa according to DSM-5 criteria
5. Weight recovered at the time of study inclusion (body mass index > 17.5 kg/m2)
6. Greater or equal to 2 standard deviations scores of eating disorder-relevant behaviors on the Eating Disorder Inventory-3 and Eating Disorder Examination Questionnaire
7. The following types of psychiatric medications are allowed: antidepressant, anxiolytic, atypical antipsychotic, mood stabilizers
8. English is primary spoken language

Weight-Recovered AN Exclusion Criteria:

1. Pregnancy or lactation
2. Electrolyte, blood count, kidney function or liver function abnormalities
3. Psychosis
4. Neurocognitive disorders including dementias or traumatic brain injury that is symptomatic
5. Current alcohol use disorder (AUD) or substance use disorder (SUD) according to DSM-5 criteria
6. Uncontrolled hypertension
7. Hepatic impairment (Class-Pugh b or c)
8. Diabetes mellitus
9. Family history of porphyria
10. History of recent heart attack, vascular disease, or any other current acute medical conditions as determined by the principal investigator
11. Inability or unwillingness to adhere to the TKD diet for the duration of the study
12. Blind or illiterate individuals

Underweight AN Sub-Study Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Persons, aged 18 to 45 years
4. Anorexia nervosa according to DSM-5 criteria
5. Current Body Mass Index (BMI) at the time of study inclusion of 16.0 to 17.49
6. An elevated EDE-Q global score of 2.09 or greater
7. The following types of psychiatric medications are allowed: antidepressant, anxiolytic, atypical antipsychotic, mood stabilizers
8. English is primary spoken language

Underweight AN Sub-Study Exclusion Criteria:

1. Pregnancy or lactation
2. Electrolyte, blood count, kidney function or liver function abnormalities
3. Psychosis
4. Neurocognitive disorders including dementias or traumatic brain injury that is symptomatic
5. Current alcohol use disorder (AUD) or substance use disorder (SUD) according to DSM-5 criteria
6. Uncontrolled hypertension
7. Hepatic impairment (Class-Pugh b or c)
8. Diabetes mellitus
9. Family history of porphyria
10. History of recent heart attack, vascular disease, or any other current acute medical conditions as determined by the principal investigator
11. Inability or unwillingness to adhere to the TKD diet for the duration of the study
12. Blind or illiterate individuals

Bulimia Nervosa Pilot Inclusion Criteria:

1. Provision of signed and dated informed consent form
2. Stated willingness to comply with all study procedures and availability for the duration of the study
3. Persons, aged 18 to 45 years
4. History of bulimia nervosa according to DSM-5 criteria
5. An elevated EDE-Q global score of 2.09 or greater
6. The following types of psychiatric medications are allowed: antidepressant, anxiolytic, atypical antipsychotic, mood stabilizers
7. English is primary spoken language

Bulimia Nervosa Pilot Exclusion Criteria:

1. Pregnancy or lactation
2. Electrolyte, blood count, kidney function or liver function abnormalities
3. Psychosis
4. Neurocognitive disorders including dementias or traumatic brain injury that is symptomatic
5. Current alcohol use disorder (AUD) or substance use disorder (SUD) according to DSM-5 criteria
6. Uncontrolled hypertension
7. Hepatic impairment (Class-Pugh b or c)
8. Diabetes mellitus
9. Family history of porphyria
10. History of recent heart attack, vascular disease, or any other current acute medical conditions as determined by the principal investigator
11. Inability or unwillingness to adhere to the TKD diet for the duration of the study
12. Blind or illiterate individuals