I did kenpo for years at around 300 pounds. I've been overweight most of my life. It was hard, but over time I developed an extremely powerful cardiovascular system, and was able to outlast many of my peers in fights. I still couldn't run though, I'd get winded almost immediately.
I started the power 90 program and went on a drastically reduced diet. I also stopped drinking soda and started pushing water heavily. I got all the way down to 190. At the time I was also teaching kenpo 5 days a week full time.
In my experience, and from what I've read, the only real way to lose weight is the one nobody wants. Diet and exercise. Turns out they were right all along. If you control your diet, push fluids, and exercise at least an hour a day, six days a week, you will definately lose the weight. Unless you have a glandular problem, losing weight is possible for everyone, they just have to do the hard work, which is kinda like martial arts in that sense.
I'm not attacking you, I don't want to come across that way. I'm saying that if you really want to lose weight, the good news is you can! It's not easy or fun, but you'll end up looking sexy, and that's really what we all want right?
Oh, and you'll be able to run and do jump kicks, and if you can fight when you're heavy, you'll fly when you're thin.
-Rob