Background and purpose: Ketogenesis is a physiological phenomenon due to starvation or a ketogenic diet (KD), a drastic restricted carbohydrate dietary regimen that induces lipid metabolism and ketone body synthesis. Two patients whose migraines disappeared only during, and not outside, cycles of very-low-calorie KD performed to reduce their weight were recently observed. To confirm our observation, in a dietitian clinical setting two parallel groups of migraineurs, one receiving a 1-month very-low-calorie KD prescription followed by a 5-month standard low-calorie diet (SD) and the other a 6-month SD, were followed. Methods: Ninety-six overweight female migraineurs were enrolled in a diet clinic and blindly received a KD (n = 45) or an SD (n = 51) prescription. Mean monthly attack frequency, number of days with headaches and tablet intake were assessed before and 1, 2, 3 and 6 months after diet initiation. Results: In the KD group, the baseline attack frequency (2.9 attacks per month), number of days with headaches (5.11 days per month) and tablet intake (4.91 doses per month) were significantly reduced after the first month of diet (respectively 0.71, 0.91, 0.51; overall, KD versus baseline, P