uh, you can't do anything?
I can understand (personal empathy here) holding off on squat, clean and DL, but hey, you can probably still press and bench. Do you have access to sissy machines (universal) that you could brace your back on? Could minimize detraining completely this way maybe.
Look hard at what you can really do, and try to stay active. As someone with recurring back issues, I have found I heal much quicker when I get back into things quicker (just be judicious, of course).
As for the diet part, I don't know your age/weight etc, but my guess is it's ok to scale back based on decreased activity levels.