There's no easy way to say "I wanted a big fat bad guy called Gullet."
Really, the name and imagery came to me all at once, it was just a factor of nailing down what the look would be. I knew he'd be big and fat and he'd have a distorted face. But I wanted something a big more memorable with the design. Nothing clicked until I decided to "Kirbyfy" it a bit, and try to make it a bit like a character the late, great "King" Kirby would design. The banded metal arms and blast furnace for a stomach helped finish the design.
For his powers, I saw Gullet as someone that was accidentally merged with some form of energy field. The field didn't provide power on it's own. He'd have to "Feed" it. And it fed on any solid matter. In return, he'd gain increased strength and durability. However, the process would also warp and distort his body to ill effect, transforming him into the grotesque blob that he is in the picture. He'd down a car for a quick boost of strength. Or down a telephone pole to gain enough energy to fire a blob of toxic plasma out of his maw. The more he ate, the bigger and more powerful he got. Making the key to defeating him finding some way to upset his appetite, and curb his hunger.
Awesome idea and execution.
Another thing I have been similarly struggling with is how to make Fat characters unique, which is what you've done here. Unless its the Blob from X-men, it really isn't all that interesting. But what you've done here really makes him stand out in terms of design, origin, powers and drawbacks to said powers. It really sets him apart from other fat guy characters.
The 'Kirby Krackle' really does sell the design!