The way I look at it, we already have all of this, but the nuances have to be evolved, not hard wired and fixed in the sim.
Nrg is the primary limited resource in the sim which bots compete over. If bot A is feeding on bot's B nrg, that reduction of nrg in bot B is a type of injury. Lower nrg means less ability to reproduce or even a complete inability to reproduce, depending upon the nrg threshold bots use to do so. It menas less nrg to do things. Reduced capability to do things is injury. Yes, bots can evolve to reproduce at a lower nrg level, but conveying les nrg on your offspring is a disadvantage and likly to reduce funcundity in a competitive ecosystem. Bots can use body to replenish lost nrg, but they must have the genetics to do so. Using body to replace nrg is better than not having the ability to do so, but having less body has impact on a bot's ability to attack, less potent feeding, etc.
I'm all for making the resoruces a bot has aquired - nrg level and size in terms of body - more directly relatable to attack / defense ability. We could for example, create a relatonship between movement speed and the cost to do so, perhaps even a non-linear relationship so sprinting distance X takes a LOT more nrg than walking that same distance even though the latter takes more cycles, but in general, I oppose adding hard wired rules to the system. If it can be evolved, it should be evolved.