When carrying a pack of pretty much any size and weight and using the hip belt, my left leg will go numb sometimes. The problem goes away if I loosen the belt, but this defeats carrying the weight on my waist. (I've been fitted by knowledgeable people.)
Submitted by - Chris, Sherman, TX
Your problem is not uncommon, but, alas, there is little to be done. If the numbness or tingling stays on the surface of your leg (skin level) it is unlikely anything serious is going on. Nerves in the hip area just don't like the pressure. Sometimes a different hip belt will alleviate the problem, but it sounds like you've tried that. If the numbness is deep, causing you to stumble or feel like you might stumble, I suggest you tell the tale to your local doc.