A method of controlling obesity by physically narrowing the lumen of the pylorus One embodiment includes injection of a bio-compatible bulking or stiffening material into the pyloric sphincter area of the stomach. The injection of this material bulks the pyloric sphincter, narrowing the lumen, retarding stomach emptying and producing a feeling of satiation in the patient. The method may be practiced or supplemented by cauterization of the pyloric sphincter or by suturing the sphincter to narrow the same and may be augmented by inducing flacid paralysis of the stomach by injecting botulinum toxin into the muscle tissue of the antrum or fundus of the stomach.