The Bear Boxer Contender is _claimed_ to have room for 3 days worth of food, and the Champ is _claimed_ to have room for 7 days. Repackage that with a large grain of salt, because the Contender is 275 cubic inches, and the Champ is 608 cubic inches.
I find it almost impossible to pack one day's worth of food any tighter than 100 cubic inches. But that is just me. Imagine a slab of coffee cake that is 10 inches by 10 inches by 1 inch thick. That would be your food volume for one day. That's tight.
On the other hand, I have an old Garcia (615 cubic inches) that I packed one time for a 9-day trip, or 8.5 food days. However, I would have lost weight on that trip.
I don't think that it can be said often enough that repackaging food makes a huge difference.