Participants close to the creature of gluttony were overtaken by the desire to eat.
They were so lost in their act of eating that they forgot about their well-being. They didn't care that the creature of gluttony was eating them.
Their mouths were painted in black blood and chunks of meat were stuck in their now-grown teeth. They also started developing various cavities on their bodies which were eventually turned into mouths.
The participants were becoming creatures of gluttony themselves by eating one another. One could say that they had taken "you are what you eat" to an extreme.
Over time, both participants and the gluttonous creature's flesh would regenerate. However, it seemed like the creature of gluttony would be able to eat them before they could eat him.