BACKGROUND AND AIM: Prospective trials evaluating efficacy of specific diet restriction in functional dyspepsia (FD) are scarce. We aimed to assess efficacy of low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet in FD, compared with traditional dietary advice (TDA). METHODS: In this prospective, single-blind trial, patients with FD (Rome IV) were randomized into low FODMAP diet (LFD) and TDA groups, for 4 weeks (phase I). In phase II (4-12 weeks), LFD group was advised systematic re-introduction of FODMAPs. Symptom severity and quality of life were assessed using "Short-Form Nepean Dyspepsia Index (SF-NDI)." Primary outcome was symptomatic response (symptom score reduction of ≥ 50%), at 4 weeks. Study was registered with CTRI (2019/06/019852). RESULTS: Of 184 patients screened, 105 were randomized to LFD (n = 54) and TDA (n = 51) groups. At 4 weeks, both groups showed significant reduction in SF-NDI symptom scores compared with baseline, with no significant difference in inter-group response rates [LFD: 66.7% (36/54); TDA: 56.9% (29/51); P = 0.32]. On sub-group analysis, patients with postprandial distress syndrome or bloating had significantly better symptomatic response with LFD (P = 0.04). SF-NDI quality of life scores improved significantly in both groups. On multivariate analysis, factors predicting response to LFD were bloating and male gender. Incidences of adverse events (minor) were similar in both groups. CONCLUSIONS: In patients with FD, LFD and TDA lead to significant symptomatic and quality of life improvement. Patients with postprandial distress syndrome or bloating respond significantly better to LFD. Therefore, dietary advice for FD should be individualized according to FD subtype.