The aim of this project is to characterize the influence of a ketogenic diet and intermittent therapeutical fasting on the course of the disease, as measured by T2-hyperintense cerebral lesions with magnetic resonance tomography (MRT) in patients with multiple sclerosis (RRMS). The investigators expect in both intervention groups fewer cerebral T2 lesions occurring after 18 months in comparison to the control group and as detectable by MRT. According to current recommendations of the German Society of Nutrition (DGE), the control group receives a vegetarian-focused, anti-inflammatory diet.

Inclusion Criteria:

• Existing health insurance, so that in case of random findings these can also be clarified
• Patients with relapsed-remitting MS according to the MS diagnostic criteria according to McDonald 2010
• Age 18-65
• Consent ability and written consent
• BMI between 19 and 45 kg / m2
• EDSS <4.5
• Stable immunomodulatory therapy or no immunomodulatory therapy> 6 months before confinement
• In the last 2 years ≥ 1 relapse or within the last 2 years ≥ 1 new T2 lesions or ≥ 1 contrast-sensitive lesion in MRT
• Consent that possible random findings are reported

Exclusion Criteria:

• Initiation or modification of immunomodulatory therapy during the study
• Cortisone treatment in the last 30 days before enrollment
• Relapse in the last 30 days before enrollment
• Insulin-dependent diabetes mellitus (type I)
• Intake of Omega 3 fatty acids (DHA, EPA) - more than 1 g / day
• Significant cognitive impairment, clinically relevant or progressive disease (e.g., liver, kidney, cardiovascular system, respiratory tract, vascular system, brain, metabolism, thyroid) that could affect the course of the study
• Malignant disease
• Simultaneous participation in an interventional study or participation in an interventional study in the last two months before study inclusion
• Clinically relevant addiction or substance abuse disorder (defined as alcohol, drug and drug abuse)
• Nicotine consumption of > 5 cigarettes per day and no willingness to stop consumption during therapeutic fasting.
• Insufficient mental possibility of cooperation
• Eating disorder
• Kidney stones
• Known metabolic disorders (e.g., fatty acid oxidation disorders, ketolysis / ketogenesis or glucogenesis disorder, hyperinsulinism (e.g., nesidioblastoma), pyruvate carboxylase deficiency)
• Therapy with oral anticoagulants (e.g., Marcumar)
• Pregnancy and breast feeding period
• Suspected lack of compliance
• Performing of a diet for weight reduction
• Special diet for medical reasons
• Change of the body weight of more than 5 kg within one month before the start of the Intervention
• Medical, psychiatric or other conditions that restrict the patient's following abilities: to interpret the study information, to give informed consent, to adhere to the rules of the protocol, or to complete the study
• Contraindications to MRT examinations [persons with metallic implants (e.g., intracranial metal clips) and carriers of electronic devices (e.g., pacemaker) or persons with claustrophobia]