weight loss in one year

Depends on how much you work out and your metabolism/age. I'd probably say no though to 200. It's very difficult to lose much more than 100lbs in a years time. You will have slow downs and physically/mentally it is difficult to maintain that level of dedication. Every one if my friends have at one time or another commented on how my my dedication has been but I too have needed breaks. Life is still there needing your attention. You will get sick, have injuries, have family emergencies etc. I lost a bit over 100 in a year. Most people I know that have done it without surgery experienced similar results. Plus a healthy weight loss is about 2lbs per week. Granted you will have weeks you lose more and at over 300lbs that was ok with my Drs, but they didn't wanna be seeing 4-5lb losses every week either. Also I was on a 1,200 calorie diet, weighed 325 when i began the program i was in for nutrition and am 5'3" (mid 30's) and ate back only some of my exercise calories.