Background: It is uncertain whether gastric emptying of fat is determined mainly by its physical characteristics or chemical composition. In particular, the intragastric distribution of extracellular fat and the importance of that distribution to gastric emptying of fat is controversial. The effects of posture on gastric emptying, intragastric distribution, and appetite after ingestion of a meal containing oil and aqueous phases was evaluated.
Methods: Eleven volunteers consumed 60 mL 99mTc-(V)-thiocyanate-labeled olive oil and 290 mL 113mIn-labeled soup while sitting and while lying in the left lateral decubitus position. Hunger before and after the meal was recorded.
Results: In the sitting position, oil emptied from the stomach more slowly (P < 0.01) whereas in the decubitus position oil emptied faster (P < 0.01) than the aqueous phase. Oil was preferentially retained in the proximal stomach when sitting (P < 0.01), and more oil was retained in the distal stomach in the decubitus position (P < 0.05). The amount of oil that emptied in the first 180 minutes was not different between the two postures. The aqueous phase emptied much more slowly (P < 0.01) in the decubitus position. At 120 minutes and 180 minutes, subjects were less hungry (P < 0.05) in the decubitus position. In the decubitus position, hunger at 120 minutes and 180 minutes was related to the retention of oil (r > or = 0.79; P < 0.01) in the stomach.
Conclusions: These results indicate that (1) gravity has a major effect on the intragastric distribution and relatively little effect on total stomach emptying of oil, and (2) postprandial hunger is affected by posture and, in the decubitus position, is inversely related to the amount of oil that has entered the small intestine.