[DerpyMcPandos]

A bit late but I'd like to ask a niche question/confirmation of the magically formed (non-fusion) variety of Homunculi.

As we're aware, Amalgama/Salamandra follow by in large the normal rules of physiology. They

'are very similar to normal mortals by design. They may eat, sweat, cry, bleed, and so on. Although artificial, their bodies still contain necessary vital organs'

However, I'd like to clarify whether or not their artificial bodies are capable of (and if not, whether the creator can implement these capabilities) changing their body composition. More specifically:

-Can they Gain weight? (and if so, is it through normal biological processes?)
-Can they Lose weight? (and if so, is it through normal biological processes?)
-Can they Gain muscle mass (and if so, is this through exercising or some other means?)
-Can they Lose muscle mass (and if so, is this through neglecting exertion of those muscles?)

While the wiki page on Homunculi notes they do require nourishment to sustain their bodies it doesn't explicitly note whether this is only for maintaining their body as it is or whether natural biological processes can shape and change that initial state as given to them by their creator.