I could see my pack being lost because of an aggressive bear. Because there are a lot of them here, and the woods are very close-in around you. a bear on or near the trail can smell food in a backpack. If you came upon a bear suddenly, is possible that you might have to abandon your pack if the bear becomes too interested. If for no other reason than to make it easier to climb a tree or to distract the bear while you get away. It is possible the bear would just maul up the pack for the food and leave the rest, but it might also drag the whole pack off into thicker cover where I wouldn't want to go in after it. When hiking in the deep woods, I keep my food in a separate little nylon stuff sack in my pack on top of my gear so I can grab it and throw it if I have time to.