Short backpacking trips lend themselves to fresh fruit and vegetables, tasty and elaborate backpacking meals, and s’mores. A long-distance thru-hike, not so much. You starve yourself because you never carry enough calories to make up for all the ones you’re burning, and the most calorie-dense foods are not very good for you. Here are examples of food that I and other hiker trash lived off of for six months.
List: Appalachian Trail food
Yeah… not so healthy, but lots of calories