High GI carbs post workout

I know how to get into shape, I just am not sure on how to stay in shape. It is 4 weeks after my show and I swear that I am gaining weight even though I am eating clean and working hard. I am still around 5-6% but I am afraid that it will keep climbing. As for high GI carbs, is it optimum to take 100gms of a maltodextrin based drink with protein within 20 minutes of your workout? Would a carbo force 109gms maltodextrin and a lean body bar work? Need to understand this as I have been avoiding high GI carbs like the plague for the past 15 weeks.