Mediterranean Diet vs. Time-Restricted Eating: Effects on Circadian Rhythm and Appetite Markers in Female Patients with Multiple Sclerosis—A Pilot Study

Background/Objectives: Multiple sclerosis is frequently associated with sleep disturbances and circadian rhythm disruptions. This study evaluated the effects of the Mediterranean diet (MedDiet) (n = 17) and time-restricted eating (TRE) (n = 17) on sleep, chronotype, and appetite-related parameters in females with relapsing–remitting MS. Methods: In this 12-week randomized comparative pilot trial, 34 female patients with RRMS were randomly assigned to either a MedDiet or TRE (16:8 protocol) group. Individualized eucaloric diet plans were provided to maintain baseline weight. Biochemical parameters (fasting glucose, lipid profile, leptin, and ghrelin levels), anthropometric measurements, the Pittsburgh Sleep Quality Index (PSQI), the Morningness and Eveningness Sleep Questionnaire (MEQ), and dietary intake were assessed at baseline and week 12. Results: Both groups showed significant reductions in body mass index, waist and hip circumference, although no statistically significant changes were observed in reported energy intake. In the MedDiet group, LDL (101.88 vs. 99.12 mg/dL) and total cholesterol (178 vs. 173 mg/dL) decreased before correction for multiple comparisons (p < 0.01); however, these findings did not remain statistically significant after multiple-comparison correction. Leptin and ghrelin showed no significant changes in either group. Both groups increased dietary protein, fiber, and water intake and decreased fat intake, while carbohydrate intake remained unchanged. MEQ scores increased only in the MedDiet group (p = 0.035). Mixed-design ANOVA revealed a significant time effect on PSQI scores independent of diet type (F = 11.370, p = 0.002), although this effect could not be attributed to a specific dietary intervention. Conclusions: Both diets were associated with changes in anthropometric measures. The MedDiet was associated with increased MEQ scores and trends toward favorable changes in lipid parameters, suggesting a shift toward a more morning-oriented chronotype rather than a direct effect on circadian rhythm. No significant changes were observed in sleep quality or appetite-related hormones. Further studies with larger samples and longer durations are needed.