A belt is better than nothing, but they can hurt or kill you. I fell 3 feet while wearing a belt around my waist, the 3 foot fall broke one of my ribs. But that was better than what the 25 foot fall would have done to me, I would not be here.
Two guys have already died from tree stand falls the past week, 1 in Maryland and 1 in Grorgia. And there will be more deaths before this 2008 season is over. If a hunter doesn't wear a full body harness when hunting from a tree stand, he is just plain stupid!