Impact of Intermittent Fasting on Premenstrual Syndrome among Medical Students: A Randomized Controlled Trial

Abstract

Background: Premenstrual syndrome (PMS) can impair physical, emotional, academic, and social functioning. Evidence on time-restricted eating (TRE) for PMS remains limited. Methods: This parallel-group randomised controlled trial enrolled 60 female medical students aged 18-28 years with mild-to-moderate PMS. Participants were allocated by lottery to a modified TRE intervention group (n = 30) or a control group that continued its usual routine without a study dietary intervention (n = 30). The registered intervention was scheduled from menstrual-cycle day 9 through day 28 for two months. The implemented meal schedule documented food intake from 3:00 PM to 8:00 PM; therefore, the regimen is reported here as a modified TRE regimen rather than a strict 20:4 protocol. The primary outcome was the Premenstrual Symptoms Screening Tool (PSST), and the secondary outcome was the Menstrual Distress Questionnaire (MEDI-Q). Outcomes were assessed at baseline, after month 1 and after month 2. Results: All 60 participants completed follow-up. Baseline PSST and MEDI-Q scores differed between groups. In the intervention group, mean PSST scores decreased from 33.2 ± 6.70 at baseline to 12.0 ± 4.48 at month 1 and 14.2 ± 3.94 at month 2; the month-2 score remained markedly below baseline but was higher than at month 1. Mean MEDI-Q scores decreased from 27.9 ± 4.04 to 15.4 ± 3.88 and 10.7 ± 2.89, respectively. Control-group pairwise comparisons were not statistically significant. Reported repeated-measures analyses showed significant time, group, and time×group effects for both outcomes (all p < .001). Conclusion: A two-month modified TRE and structured dietary regimen was associated with substantial reductions in PMS symptom severity and menstrual distress in this single-centre sample. Because the groups differed at baseline and the intervention combined meal timing with a specified food pattern, the findings should be interpreted as preliminary and should be confirmed in larger trials using baseline-adjusted analyses, quantified adherence, and longer follow-up.