It took me ten years of improved nutrition and increased physical activity to go from 216 to 155. Keeping at 155 in the winter is a PITA, the same amount of discipline with much less fun, i.e. riding outdoors. I agree that what you should be concentrating on is a life-style change which will allow you to reach and maintain a normal weight for you age, height etc.. With good nutrition and exercise this will happen naturally, being in a hurry to achieve your goals will probably be counterproductive. Relax and enjoy the ride.