This Open-Label Pilot Study Aims to Determine Whether a Two-Part Sequenced Out Patient Procedure Utilizing a Modified Ketogenic Diet Followed by a Series of Titrated Ketamine Infusions Results in Improvement or Remission of Chronic Anorexia Nervosa in Adults with Symptoms of Anorexia for at Least 3 Years Despite Treatment Involving at Least 2 Different Modalities. The Hypothesis is That the Diet Addresses Core Metabolic Deficits in the "Anorexic Brain" and Primes the Response to Ketamine.

Participants Who Are Deemed Eligible Will Participate in an Open-Label Clinical Trial Using a Sequenced Treatment Previously Reported in One Case Study to Result in Complete and Sustained Remission of Anorexia Nervosa for Over One Year (and Continuing).

Part 1 Involves a Group 2-Day Immersive In-Person Educational Program to Begin a Modified Ketogenic Diet, Under the Supervision of a Nutritionist Who Has Decades of Experience in Designing Ketogenic Diets for Seizure Patients. This Group Experience is Followed by a 4 Week Period of At-Home Adoption of the Diet, With Close Phone and E-Mail Follow-up.

Part 2 Involves Administration of a Series of Titrated Intravenous Ketamine Infusions Scheduled Over 2 Weeks.

During Part 1, and Part 2, There Will Be a Range of Objective and Psychological Measures To Assess Safety and Response. The Participants Will be Followed For 12 Months.

Inclusion Criteria:

• Adults Between 18 and 65
• Anorexia Nervosa Diagnosis For at Least 3 Years
• Treatment Resistance, as Evidenced by Having Failed at Least 2 Treatments
• Body Mass Index (BMI) Greater than or Equal to 18.5
• Stable Weight for the Last 3 Months (No Consistent Change Greater than 5 Pounds)
• Abstinence From Substance Abuse for At Least 3 Months
• No Cannabis Use for At Least 3 Months
• Currently Under the Care of a Primary Care Provider (PCP)
• Participant Must Agree to have PCP Contacted by Study Staff
• Willingness to Participant in a 2-Day Program in Central Connecticut
• Identified Support Partner Who Will Attend Program
• Willingness to Have Weight Recorded and Reported by PCP or Support Partner
• Willingness to Attend 4-6 Clinic Visits For Ketamine Infusion
• Willingness to Be Contacted for Follow Up for 12 Months
• Willingness to Abide By All COVID Safety Measures

Exclusion Criteria

• Concomitant Disease (Gastroentestinal, Renal, Respiratory, Cardiac, Etc) or Any Clinically Significant Finding at Screening that Would Pose a Risk to the Participant
• Primary Carnitine Deficiency, Beta Oxidation Defects, Pyruvate Carboxylase Deficiency, Porphyria, or Treatment with Carbonic Anhydrase Inhibitors
• Bulimia Nervosa as The Primary Diagnosis
• Weight Change of Greater Than 5 Pounds in Last 3 Months
• Pregnancy
• Sexually Active Females Not Using Birth Control
• Interstitial Cystitis
• Unmanaged/Unstable Hypertenison (Greater than 140 Systolic; 90 Diastolic
• Cardiac Arrythmia
• Uncontrolled Seizure Disorder or Seizure Withen 30 Days Prior to Screening
• QTc Interval of 470 ms or Greater
• Current or Past History of Psychotic Disorder
• Active Suicidal Ideation
• Enrolled in any Clinical Trial or Used Any Investigational Agent, Device, and/or Investigational Procedure Within 30 Days Before Screening, or Does so Concurrently With this Study