BACKGROUND/AIMS: Only Limited information has been provided on the effects of dietary factors in functional dyspepsia (FD). The aim of the present study was to compare the effects of different liquid meals on the symptoms and gastric electrical activities in FD patients. METHODS: In the first study, comparisons between water and a caloric nutrient drink were performed in twenty-seven FD patients and ten healthy volunteers. In the second study, a high carbohydrate liquid meal was compared with a high protein meal with the same calories, volume and fat component for the twenty-one FD patients and the ten healthy volunteers. Recording of the electrogastrography with symptom assessment was performed. RESULTS: The power ratio, the postprandial dominant frequency instability coefficient and the postprandial percentage of time with normogastric slow waves did not differ between the water and a caloric nutrient drink, and also between the high carbohydrate and high protein meals. Unlike the healthy controls, the FD patients had more severe symptoms after a caloric nutrient drink as compared to water. No difference in the symptom scores was observed between the high carbohydrate and high protein meals. CONCLUSIONS: The caloric nutrient drink is more associated with symptoms than is a non-nutrient meal for FD patients. Variations in the carbohydrate and protein composition are of no importance in the genesis of dyspeptic symptoms and gastric electrical abnormalities.