When I started training for triathlons I learned the best way to get fast is to lose weight. When I was overweight no matter how much and how hard I trained my fitness couldn't make up for the loss of speed because of the extra weight I carried. I've found out getting fat slows down a CrossFit athlete just as much. Not that long ago I'd gotten to the point that I was doing every WOD with the RX and finishing quickly. I was completing the WOD with a fast enough time that I was going to start adding more weight than the RX. But then I fell off the diet wagon and gained a crap load of weight. I'm was still working out consistently, but the weight gain has slowed me down much worse than I had imagined it could. I'm back to having to do each workout below the RX and finishing close to last every class. Dang it, body weight matters in CrossFit too.
"It is no disgrace to start all over. It is usually an opportunity. "George M. Adams