Contribution of gastric and postgastric feedback to satiation and satiety in women.

Two parallel preload studies were conducted to determine the relative contributions of inhibitory feedback from the stomach and intestine to satiation (meal termination) and postprandial satiety. In the Gastric Emptying Study, five normal-weight women each ingested an egg sandwich (307 kcal) (1) immediately after a tomato soup preload (120 kcal), (2) 20 min after a tomato soup preload, and (3) with no preload. There was 125 g more of soup in the stomach when subjects began ingesting the sandwich immediately compared to 20 min after the soup, and the emptying of the sandwich was delayed when it was ingested immediately but not 20 min after the soup. The lag times for emptying of the sandwich were 76.5 (69.1-82.4), 47.2 (20.1-67.7), and 42.4 (17.8-65.1) min for the three conditions, respectively, p < 0.05. In the Food Intake Study, 16 normal-weight women ate significantly less (p < 0.01) in test meals offered immediately (978+/-246 kcal) and 20 min (1027+/-298 kcal) after the soup preload than in a test meal with no preload (1151+/-279 kcal). Despite the different amounts of soup in the stomach, subjects' test-meal intake in the two preload conditions was not significantly different. Subjects' fullness ratings following the preloads and the test meals were not different among the treatment conditions. The results suggest that feedback from neither the gastric nor the postgastric compartment is primary in determining meal size and postprandial satiety. Instead, signals from gastric and postgastric sources are combined to determine meal size and postprandial satiety.