Several aspiring actors have asked me lately about taking off some pounds before they began trying to break into actin. No all of these people were female. First of all, there are roles for Plus Sized Actresses and Actors. Drop Dead Diva on Lifetime was a great summer series with an overweight lead, now they have another series with an overweight lead. So if you are talented and have the personality and an interesting look, you can find a role even if you are over weight.
Second, if you wait until you lose weight, you are never going to try, because I know how hard it is to lose weight (I weigh 270). But I am also very tall,so I played villians in western films. There were lots of heavy actors auditioning. Third, you need to be comfortable with who you are and if being heavy is part of that, great. That's you. Love you and be happy with you. There are so many roles for plus sized actors and actresses that there may be one waiting for you.