Effects of soup preloads on gastric emptying and fullness ratings following an egg sandwich meal.

To identify the source of inhibitory signals from the stomach or intestine that lead to satiation, the effects of 300-g tomato soup preloads on the gastric emptying of a solid meal and on hunger and fullness ratings were examined. Subjects were nine healthy women who each ingested an egg sandwich: 1) with no soup, 2) immediately after the soup, and 3) 20 min after the soup. Emptying of the sandwich was measured using radionuclide scintigraphy. Soup significantly prolonged the lag phase (period before significant emptying occurred, p < 0.05), and the half-emptying time (p < 0.01) of the sandwich, but only when ingested immediately before the sandwich. Thus, soup affected the emptying of the sandwich when the volume of soup in the stomach was at a maximum. Passage of soup into the duodenum over a 20-min period had no effect on emptying of the sandwich. Despite the different gastric/postgastric distributions of the soup and the sandwich in the two preload conditions, fullness ratings were not different.