Functional dyspepsia is common, affecting 7.2% of the global population, and associated with substantial health impairment. Almost 80% of patients with functional dyspepsia report meal-related symptoms and are classified as having the postprandial distress syndrome (PDS) variant. However, studies evaluating dietary modifications in PDS are sparse. The investigators will perform a randomised trial evaluating traditional dietary advice (TDA) vs. a diet low in fermentable fermentable oligo-, di-, mono- saccharides and polyols (low FODMAP diet) in PDS. 70 patients with PDS will be randomly assigned TDA or a low FODMAP diet. The TDA group will be recommended to eat small, regular meals and reduce the intake of caffeine/alcohol/fizzy drinks, fatty/processed/spicy foods, and fibre. The low FODMAP diet group will be advised to exclude fermentable carbohydrates, which are present in wheat-based products, many fruits/vegetables, pulses, beans, dairy, and sweeteners. Questionnaires are to be completed during the 6-week trial, including self-reported adequate relief of dyspeptic symptoms, and the validated Leuven Postprandial Distress Scale (LPDS), Gastrointestinal Symptom Rating Scale, and Nepean Dyspepsia Quality of Life Index. The primary endpoint to define clinical response will be evaluated over weeks 4-6 as \>0.5-point reduction in the PDS subscale of the LPDS (calculated as the mean scores for early satiety, postprandial fullness, and upper abdominal bloating).