I agree... I was on a 900 calorie diet before and my bariatric doc (and the program) expressly forbid strenuous activity, since 900 calories was just enough to keep me alive. I have not had surgery, it was the high protein Bernstein diet, and I was eating 200 g of lean protein a day.
Could you talk to your doc about your get-ripped

fitness goals, and recruit her/his help & input? Perhaps set a goal weight for when you can begin lifting?
I think NROL4W is a much better long term solution than chronic under-eating though. I'll bet after you've lost most of your excess weight you're going to be WAY ahead of the game for starting NROL4W. Just moving around will be so much easier!