It's extremely obvious.
Elecro never specified what sort of "eating", you can eat without biting so you wouldn't actually die.
That being said, if you are flexible enough to slide your body into your mouth from the legs up then you should be more concerned about your apparent lack of any bone structure whatsoever than whether or not you'd gain any weight.
That being said, you wouldn't gain weight as your mass wouldn't increase, it would just be in a different place