Teen fitness?

My 13 y/o brother is 40 lbs overwieght. He lost it all and then yo-yoed back up in 3-4 months. He also is a high-functioning autistic (aspergers actually for those who are informed) which makes it really hard to pry him away from his video games. He's a year round all-star athlete, his weight is just out of control! I'm looking for a way to motivate him to lose the weight again. But I want to find a way to get him interested in his health without huritng his self-esteem anymore than it has been already b/c of his differences socially.
Has anyone had a similar experience/ success story?
Also, is it bad to try and create intrinsic motivation by extrinsically motivating with material rewards?

Another important point. How do you instill cardio, or fitness in general, into an AS routine without disrupting him?

there is no reason not to motivate him using external rewards; if he is high functioning autistic, it may be enough that you tell him you are interested in learning more about games and gaming, but that you are really busy. ask if it might be possible for him to come for a walk with you and explain some concept or other gaming related.

The thing about aspergers syndrome is that his interests can be channelled (I think) and even, in time, redirected. if he associates fitness activities with gaming, he may come to be more interested in the fitness aspect.

if he isn't keen, offer extrinsic motivation as a bribe.

Try to do fun sports with him like hiking in the woods shooting hoops and other big brother stuff. Don't push him make it fun and when your done give him space.Make it a daily thing.Also I know aspergers is not like down syndrome so introduce him to some girls to get him pumped.

My little brother also has AS. And I know what you mean about the video games. I know how hard it is to help some one with AS keep them selves healthy. Personally I think the rewards thing is the best. It helps them motivate them self wile getting something in return. But when you do rewards set them loosely, not like if you lose a pound you get something. Take his favorite treat, and if he works out every day (or a few times a week) and eats healthy all week, then he gets his special favorite treat at the end of the week. In my personal experience it works the best, but you may want to consult a doctor or a specialist about it. Just to get their professional opinion. Good Luck!