A system for treating obesity, comprises an injectable compound for intramuscular administration in a pyloric sphincter, the injectable compound including a plurality of microspheres and a fluid carrier in which the microspheres are suspended. The system further comprises an injection device having flexibility sufficient to pass through a working channel of an endoscope into the stomach to an injection location adjacent to the pyloric sphincter, the injection device including a tissue piercing tip and a lumen through which the injectable compound may be delivered.