Objectives/HypothesisTo investigate the efficacy of low‐fat, low‐quick‐release sugar, high‐protein, alkaline, and plant‐based diet as single treatment for patients with laryngopharyngeal reflux (LPR).Study DesignCross‐over observational study.MethodsPatients with LPR diagnosis at the hypopharyngeal‐esophageal multichannel intraluminal impedance‐pH‐monitoring were prospectively recruited from the reflux clinic of three University Hospitals. Patients were instructed to follow low‐fat, low‐quick‐release sugar, high‐protein, alkaline, and plant‐based diet for 6 to 12 weeks. Pre‐ to post‐treatment symptom and finding changes were evaluated with reflux symptom score (RSS) and reflux sign assessment. Findings were compared to those of a control period where patients did not receive any treatment or diet. Diet was evaluated with refluxogenic diet score (REDS).ResultsFifty patients completed the study (19 males). Otolaryngological, digestive, and total RSS scores significantly improved from baseline to 6‐week post‐diet, while there were no significant changes during the control period. At 6‐week post‐diet, 37 (74%) patients reported significant symptom improvement or relief. Among them, symptoms continued to improve from 6 to 12 weeks in 27 cases, corresponding to a diet success rate of 54%. The REDS was predictive of the baseline RSS (P = .031).ConclusionLow‐fat, low‐quick‐release sugar, high‐protein, alkaline, and plant‐based diet is an alternative cost‐effective therapeutic approach for patients with LPR. Patients with higher REDS reported higher baseline symptom score.Level of Evidence3 Laryngoscope, 132:1916–1923, 2022