I find for a long walk, over 6 miles, a nice wholesome banana, a chai late with fat free 1/2 & 1/2 (watch the sugar in some of these) and an occasional Shot Block will get me where I'm going. Oh, yeah, and water, lots of water. If you walk past the port-a-potties at 2 checkpoints in a row you probably aren't drinking enough. I have also found that Zone bars are wheat free and quite tasty. I found this is a good wheat free meal replacement for all of those sandwiches they give the walkers (and runners, bikers, etc). Because of food allergies that is pretty much what got me through 17 miles this past May. Most walk-a-thons have 'carb loading' snacks loaded with wheat so I have to be prepared with a pouch of healthy complete snacks which will get me through. Other walks I have taken small single serve bags of nuts, dried meat like beef jerky, or dried fruit. It might sound strange but I have considered getting a bag of the Gerber Graduates for Toddlers Mini Veggies toddler sweet corn snack (freeze dried corn) to take to the next long walk. It is really tasty, healthy, light weight, and wheat free. The Iroquois were able to go great distances on dried meat, dried corn, nuts, and berries. It worked then and it still works now.