I can't think of a supernatural force is like "sh!t on normal things. You can be friggin supernatural thing, too.
But... Remember about chrolophyll(green pigment) plus you need h20 for respiration and humans don't diffuse water through their skin.
Do you know that a species of sea slug has started to produce a chemical similar to chlorophyll and has started to go under photosynthesis and the Kreb's Cycle? It is the first animal to do so. So who knows? It might be a possibility.
!!! When you enter magic into the equasion even normal equations like e=mc2 become things like e=McHammer
But why can't you enter it into the equation? We've already entered a "sky bully", extraterrestrial sex, and uncomprehendable luck with no true knowledge of a beginning for our existence here. If one of those are right then why can't magic be included as a possibility for someone to survive without eating or drinking?