I didn’t even know that I have a pyloric sphincter valve! But the BBC says that I do, and that it can be made to shut with the eating of soup, and that’s a good thing for weight loss:
After you eat a meal, the pyloric sphincter valve at the bottom of your stomach holds food back so that the digestive juices can get to work. Water, however, passes straight through the sphincter to your intestines, so drinking water does not contribute to “filling you up”. When you eat the same meal as a soup, the whole mixture remains in the stomach, because the water and food are blended together. The scientists’ scans confirm that the stomach stays fuller for longer, staving off those hunger pangs.