Eligibility for the run-in phase of the study:  Participants will be eligible to enroll in the fourteen-day run-in phase of the study if they meet the following inclusion and exclusion criteria:  INCLUSION CRITERIA:  A definitive diagnosis of RRMS based on the 2017 revised McDonald Criteria. The ability to prepare, or availability of someone to prepare, home-cooked meals. Must own a computer, smartphone, or tablet device that has internet access to complete online surveys and capable of running study related applications. Must be willing to follow study procedures outlined and explained to them. Be between the ages of 18 to 70 at the time of consent. Must be able to walk 25 feet without support. Willingness to be randomized and follow any of the study diets. Must consent to sharing the clinical notes from their primary care and neurology providers during the study period. Must live within an approximate 500-mile radius of Iowa City OR live in one of the following states: Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, Ohio, South Dakota, or Wisconsin.  EXCLUSION CRITERIA:  Moderate or severe mental impairment. Use of insulin, Coumadin, weight loss medications such as orlistat that causes fat malabsorption. Worsening of symptoms resulting in the initiation or change of treatment including steroids (solumedrol, prednisone, etc.) or disease-modifying medications in 12 weeks prior to consent. Treatment for cancer by radiation or chemotherapy in 12 months prior to consent, other than skin cancer. Diagnosis of clinically significant heart disease, liver disease, kidney disease, or history of oxalate kidney stones. Diagnosis of type II diabetes that does not have approval from treating physicians to adopt any of the 3 study diets. Clinical diagnosis of moderate to severe psychiatric disease that makes study adherence more difficult (e.g., schizophrenia, bi-polar disease, severe depression and/or anxiety). An active eating disorder such as anorexia, bulimia, binge eating, or orthorexia. Measurement of BMI <20 or >40. Confirmation of pregnancy or planning to become pregnant in the next 2 years. History of diagnosed fat intolerance/malabsorption such as cholecystectomy or uncontrolled exocrine pancreatic insufficiency. Participation in another research study investigating MS treatments, diet, or exercise. Presence of a contraindication to completing a brain MRI or having claustrophobia which interferes with completion of MRI studies without the use of sedation.