Protoss gain nutrition from sunlight, or at a pinch, moonlight (which is just reflected sunlight anyway) by absorbing through their skins. They can go for extended periods without absorbing sunlight. What little moisture they need is also absorbed through their skin."
So what do you think about it? Did you have your own theories about what do protoss eat? I always was sure in some kind of psi-synthesis they use (like photosynthesis, but using psi-energy). They surely gain carbon through air they breathe (CO2) and probably gain some minerals through water, but anyway there's not enough elements to build a body. May be psi-synthesis includes transmutation of elements?