Hiking is probably always going to give you a better chance of losing weight than not hiking.

The answer you get to any question depends on the bias of the group you're asking. Go to a hard-core ultralight hiking board, and they'll tell you you're not doing it right if you carry more than 10 pounds total, or want to be comfortable.

Keep at it; any exercise is better than no exercise. Just remember to look at your eating habits (sounds like you already are) - the combination of healthy eating and more exercise will help get the weight off. It may take time, but keep at it.