It's 50% a bug and 50% a feature request

the C.M.G. from industrial foregoing consumes the eternal steak, it's a block that converts food's saturation into Forge energy.
Maybe you could make it fuel it for ever or give it like a ridiculously high value?
That's it thanks!

Unfortunately it doesn't seem to be possible to change the FE values right now, and it's not possible to prevent it from being used as a fuel either. I'll keep this open as a reminder in case this changes in the future

and it's not possible to prevent it from being used as a fuel either

Well, this actually is possible. You can avoid registering food properties for your EverlastingFoodItem, and handle effects of it's usage yourself, so that vanilla or other mods do not recognize it as regular food item.

I'm aware I can simply remove the food component, but I doubt this would fix more issues than it would cause. I'd like to maintain compatibility with AppleSkin at the very least, which currently doesn't provide an API.