It's not so much the matter of a casual hiker starving to death on a short trip but you have to take into consideration that not getting enough food will make you tired, dizzy and that much more liable to doing something dumb. Like maybe slipping on a wet rock and breaking your neck. It happens all the time - what starts as a minor inconvenience might, with a little bad luck, eventually lead to something more serious. That's why food is an important factor, though it may be relatively low on the survival priority list.

IME food becomes much more critical in a cold climate. Carrying a heavy pack, walking and climbing long distance plus the effort required to set up a decent shelter and gather firewood, it adds up quickly. You could easily burn 5-6.000 calories per day and that is a lot, probably a fair bit more than you are physically capable of eating. I know I couldn't eat that much on a trek even if I had plenty of food. It just feels too much for the stomach to handle but not eating enough will wear you down quickly in the cold. I hear some armies that operate regularly in the Arctic get around that problem by issuing special extra-caloric rations so you don't have to stuff yourself with ungodly amounts of food but still get enough energy to keep you going.

While not practical for summer treks I always pack some smoked bacon in the winter. A pound usually lasts me 2 or 3 days and it doesn't go bad when it's cold enough. The energy boost is amazing and lasts a long time. Plus wholewheat biscuits, nuts, canned tuna and some chocolate and dried fruit and I'm good to go. I suppose it would give some touchy-feely dietician a heart attack but it really works and after all, it's tried and true.

As for getting enough food in the bush, I don't think it would work in my environment. Gathering anything close to a decent amount of wild edibles would only be feasible in the summer. Realistically, to get enough food in the longer term you'd have to hunt bigger game, which on the other hand would require an effective long range weapon and a proper set of skills.