What about having 2 bars : a sort of stamina/will bar that gets drained by attacks and non-swallowed grab, and a health bar that only gets drained when swallowed so that to allows us to enjoy the vore. The lower the stamina/will, the harder it is to struggle out of a grab, but it regens when being swallowed, or through items/consumables?
I think it would be nice to have more details on the sprite, to be able to see more of the weight gain and such.
Anyway, enough rambling about ideas, love that you're working on this game more. It's nice to see a promising 2D sidecroller vore game!