Objectives: The role of dietary restriction in the management of patients with migraine is still a controversial topic in the headache field. The aim of this study was to evaluate the efficacy of dietary restriction on migraine attacks. Methods: Patients diagnosed with migraine without aura according to the International Classification of Headaches were enrolled. Our study included 350 migraine patients evaluated at the neurology headache outpatient clinic. They were randomly divided into two groups: diet group as the study group and medication group as the control group. We told migraine patients to make lifestyle changes, especially those with low glycemic index in the diet group. On the other hand, propranolol, amitriptyline, flunarizine, and topiramate were used for the prophylaxis in the medication group. The frequency and severity of attacks [using the visual analog scale (VAS)] were recorded before starting dietary restriction and 1 and 3 months after the dietary restriction. Results: There were 350 participants in this study. After 3 months, a total of 147 patients (male/female: 17/130, mean age: 34.7±5.9) were evaluated in the diet group. The control group consisted of 147 age- and sex-matched, randomly selected patients with migraine without aura. In the first month after dietary restriction, monthly attack frequency significantly decreased in both groups but not the VAS score. The mean scores of VAS significantly decreased later in the diet group compared with those in the medication group (after 3 months). Conclusion: The results of the study revealed that low glycemic index diet intake can be an effective and reliable method to reduce migraine attacks.