The Gluttony skill is a special skill. It can be found ONLY as a bonus on the Wrists of the Glutton item you can unlock from the Genie Lantern building at Springlade.
Gluttony increases the bonuses you get from consuming food in combat, by providing a direct bonus of 1pt in Gluttony = 1pt of bonus.
For example if you consume a piece of food that heals 10 health, and you have a Gluttony value of 50 you actually get 60 health from consuming the item.
This effect only works in COMBAT!