Semi-realistic Regeneration and corresponding Increased Consumption

[Bruno]

Originally Posted by vicky_molokh

Due to closer scrutiny towards certain mutations and biomods, I'm interested in making the Regular Regeneration (1HP/hour) biomod at least semi-realistic in my campaign.

I always like looking at this sort of thing. It's an interesting mental exercise.

Originally Posted by vicky_molokh

...just how much extra food would be required when the organism kicks into such a high gear? I'm assuming at least some of the damaged-but-retained biological material could be recycled by the nanites/weird-phagocite-and-mobile-stem-based-repair-cell-system, though I'm not sure at which point the semi-realistic turns into outright physics-defying.

Recycling material almost certainly involves some scary waste products - diseases like malaria and ebola rapidly dismantle cells, which produces a lot of chemical byproducts. Doing it quickly overwhelms the liver and kidneys (which both diseases make worse by directly attacking of course, but we'll assume the magic regeneration thingies have the sense not to do).

So you'd probably have a requisite of a boosted liver and kidneys if you want to go this route.

You also need to reclaim fluids that have been leaked into places they shouldn't go. That can be tricky, you'll be fighting the bodies natural inclination to swelling. There's also the cell-filled fluids and tissues that are flat out not in your body any more so there's limitations.

Originally Posted by vicky_molokh

But even while building materials can be somewhat recycled, energy needs to come from somewhere - just how energy-intensive would be a 50-fold boost of healing, in terms of extra food consumption?

Faster than the digestive tract can help with if you're hoping to get it by eating after the injury, I suspect.

Originally Posted by vicky_molokh

Finally, how much of a buffer can be retained by using additional internal storage of nutrients/slow energy, purely through improvements to the biochemistry of storage (i.e. without resorting to making the person fat)?

If you're not storing it as fat, then you must be storing it as sugars, which is pretty unheard of for mammals (tetrapods in general I think) but I don't see why you couldn't do it in genetic engineering or with nanites or with a sugar-water fuel tank or whatever. But you need more than just energy - you need all the nutrients, because that's what people are made of and you'll need to rebuild things.

If it's "only" a hole poked in you or a cut, then you need to build the scaffolding for new tissue, new tissue, and new blood volume (where's the water coming from?). We'll handwave how the nanites align your tissues correctly and keep them that way while healing without you being strapped in place.

If you've had major tissue damage (fire, chemical burns, the kinds of trauma that takes flesh right off you even if it's not a GURPS amputation that you need Regrowth for) then you need to magic that material out of somewhere. And the logical place for that is your other bones and muscles.

The most obvious way to store the reserves is extra-heavy bones and excess "unsupported" muscle mass that is dismantled by the nanites and relocated to where it's needed.