Well I don't reply here much but I have to here. I have a son who now is 10u55 He decided to go to Liberty a few years ago at 8u40 He was like your son He weight 41 lbs he was wrestling 43 in Kansas. Most of the stuff they have told you here like spiting and running may work on kids who weight more but I well tell you it does not work on a boy like mine.It well work but it takes a lot more time. Plus Its hard on them not to be kids We ran every nite in sweats We did'nt eat no candy or pop all week we went to both practices Never ate nothing but popcorn all friday.7.5 hour drive.When he got on the scales it read 40.00 the guy says boy that is about as close as you get.Plus he took a wizz right before.I ask the guy if I could weight. Sure he said I lost 22 lbs! But I weight 220. Would we do it again maybe.I tell you all of this because 1 lb for a 40 or 50 lb kid it alot different than a 90 lb kid They have no fat and less water.