Question - Am I too fat to start?

I know that sounds like a horrible title, but it's a serious question.

I'm 33 years old. 6'1" and 295 lbs. I am interested in martial arts and have been since I was a teenager. Would starting something like this be too much for me at my age and weight? Should I lose weight and then begin? Should I expect to lose weight while training?

Thanks for your time.