A couple of points:

1) Since he waited to walk out until "17 days AFTER the food has ran out" he was fasting for those 17 days plus the length of his walk. Hunger should disappear after 4 or 5 days and if he kept hydrated, which he seems to have he made it through the survival situation fine. He could have probably last a few more weeks if he had to.

2) Most people have no have no idea how many calories are required to live in the wilderness for months at a time. Normally I uses the standard 57KCal/Kg of body weight per day. That means 2 1/2 times the calories you would normally eat in a day.

3) Living off the land is very hard and in many areas not particularly practical. That's why the native peoples of the areas where nomadic. i.e. they moved to where the limited games was!