It is expected that a dietary intervention based on the traditional Mediterranean food pattern should be associated with a reduction in fast-food consumption but this has never been tested before. We assessed the impact of a 12-week dietary intervention, promoting the adoption of a Mediterranean food pattern, on fast-food consumption among seventy-one healthy women aged between 30 and 65 years. The dietary intervention consisted of two group sessions and seven individual sessions with a dietitian. To determine the Mediterranean dietary score (MedScore) and fast-food consumption, an FFQ was administered. During the 12-week intervention, the MedScore significantly increased (from 21·1 (sd 3·6) units at baseline to 28·6 (sd 4·4) units at week 12, P < 0·0001), while the fast-food consumption significantly decreased (from 51·7 (sd 46·4) g/d at baseline to 20·5 (sd 18·2) g/d at week 12, P < 0·0001). Moreover, women who had a higher consumption of fast food at baseline decreased their fast-food consumption to the most (r − 0·50, P < 0·0001). When four subgroups were formed on the basis of median values of Medscore and fast-food consumption changes, it was found that only the subgroup of women which increased the most their MedScore and decreased the most their fast-food consumption experienced a significant decrease in BMI (P < 0·01). In conclusion, a dietary intervention promoting the Mediterranean food pattern led to a decrease in fast-food consumption among healthy women even if it was not a specific target of the intervention. Dietary strategies for increasing intake of healthy foods may be a useful approach for decreasing intake of less healthy foods.