We have all been told that — contrary to conventional wisdom — it is really hard to lose weight while training for a marathon. In fact, a lot of people gain weight when they up their training mileage. Personally, after 21 marathon training cycles, I know these struggles all too well. (There may be people out there who start running and watch the pounds melt off; I am not one of them.) But I also think it is pretty unhelpful to say “It can’t be done,” and as I recently learned while completing a cut on the RP diet and simultaneously training for a BQ-pace marathon, it can be done.