Atrophy (wasting away) of the stomach weakens the perception of hunger, since the perception is controlled by the percentage of the stomach that is empty.
This non-sentient material included higher plants, microorganisms, and the more degenerate metazoan endoparasites which, they argued, had nervous and sensory systems that were almost atrophied.
Facial muscles may be involved which lead to atrophy of facial muscle groups producing a thin, expressionless face with some having difficulty with chewing.