One of the effects of the hallucinogen psilocin in psilocybe mushrooms is that the brain doesn’t filter any of the sensory stimuli that it receives. This is in large part what tripping is: sensory overload.
Maybe one of the reasons we get tired in the evening and need an 8 hour restful sleep each night is because our brain works nonstop all day interpreting the signals it receives from our eyes, ears, nose, mouth, and skin. Differentiating the useful information from the noise.
Maybe we can sustain ourselves by drinking water and smelling food. By virtue of our being able to smell an entree, we are inhaling molecules which belonged at one time to the food we see before us. There must be some substance to the smell. Execute a controlled experiment: identical twins living in two houses of identical manufacture, one house at all times thick with the scent of a multitude of various fine foods, the other house always scent free. Each twin made to drink 2 liters of water over the course of each day for ten days. At the end of it I hypothesize the restaurant house resident will be better off.