teach my 10 year old little brother to losing fat

Of course he wants to play video games.  I'm 21 and I still want to play video games all the time!

But seriously, just take him with you to do active things.  Talk to your parents and get them to help out.  I was always a fat kid and I regret not being active - you'd be doing him a huge favor.

...yeah. You do not want to make him lift at 10. I know that you can start early, but that's stretching it a bit. It won't stunt his growth, but his body is still going through too much development. Wait until he's 14-15.

To get him back in shape, just make him do something fun that kids like. I dunno, play tag/basketball/soccer/etc. I forgot what I did at 10 You don't want any structured exercises or routines, that's gonna make him bored and not want to exercise ever again. Also, as people already said 1000 times, make sure he doesn't get his hands on junk food and your parents are managing his nutrition properly.

High rep/low weight is good, but think of it from a mental aspect. Your bro is gonna get fed up with working out. That is not what 10-year-olds do, unless they are being prepped to be the next world champions. He's gonna get so tired of working out and bored. Once you stop pushing him, he'll stop and any progress will backfire. You gotta get him active, but not in the routine kind of way.

Google "why is aspartame good for you" (there will be no positive results) and "why is white bread bad for you ". Some of the replies surprise me, as if this was not Ask Scooby forum.

Dance Dance Revolution my friend!

But on a serious note just cut out or limit junk foods and especially soft drinks. I remember being pretty chubby myself at 10 years old and I immediately decided to cut out soft drinks and was already beginning to feel better and look better. Applied with more physical exercise like running outside, soccer, football, tag and those kinds of things I became much more leaner and healthier