Why can't I?

Ok, this picture is a man named James, who lost 313 lbs in a year's time. THAT IS PHENOMENAL! He did have a lot of help in the beginning with his fitness guru living with him for the first 3 months of this year to teach him everything he needed to do. But he also lost 90 lbs on his own after that, and that's a lot of weight in a 3 month period. If he can do that, why can't I lose 50 lbs in a year? Granted, I'm not 651 lbs to start, with that much weight to lose, but I don't think my goal is unrealistic. 1 lb a week is a very healthy pace to be losing weight. I'm not expecting instant results. I want them to be slow and steady so that I know I'm losing it the right way. Plus, I don't want the saggy skin thing that can go along with drastic weight loss, so if it comes off more slowly, I don't get that quite so much.
So, I've figured out what my main struggle is. I need a food game plan. I have these things that I roughly follow, (Weight Watchers, and a diet plan I got from a friend) but that doesn't seem to be enough for me. I'm considering setting up an appointment with a dietician a time or two to see what would be best suited for me. I want this to happen for me, so I need to learn what is best for me. That's the one thing about weight loss. We all need slightly different things. Yes, we all need a healthy diet and to exercise to lose weight, but our bodies adapt to different things. Am I crazy to be considering this?