BACKGROUND AND OBJECTIVES: The low fermentable oligo-, di-, mono-saccharides and polyols (FODMAP) diet is an effective dietary intervention for irritable bowel syndrome (IBS), yet up to 50% of patients fail to re-spond adequately. Identifying reliable predictors of response could optimize treatment selection and improve treatment outcomes while avoiding unnecessary dietary restrictions. This narrative review examines current evidence for predictors of response to the low FODMAP diet and highlights gaps in knowledge that must be addressed to develop clinically useful indicators for routine practice. METHODS AND STUDY DESIGN: We re-viewed the literature on the low FODMAP diet, and studies investigating factors that may predict treatment response, including clinical, diagnostic, biological, biochemical, and microbial markers. RESULTS: Several po-tential predictors to the low FODMAP diet have emerged, including baseline symptom severity, psychological factors (particularly depression), hydrogen breath test results, volatile organic compounds in fecal samples, and specific gut microbiota profiles. Clinical and psychological measures show the most immediate potential for implementation due to accessibility and established measurement tools. Biological markers, including breath testing, metabolomics, and microbiome analysis, show promise but require further validation in larger, diverse populations and standardization of methodologies. CONCLUSIONS: Despite promising research, signifi-cant gaps remain in developing reliable, accessible predictors of response to the low FODMAP diet. Future research should focus on validating simple clinical tools that combine symptom profiles with psychological assessment to guide treatment decisions. A personalized approach to dietary management of IBS based on reliable response predictors would optimize clinical outcomes while minimizing unnecessary dietary restriction and healthcare resource utilization.