TI'm fascinated by various internet posters who intimate that they can walk dozens of miles, while munching skimpy amounts of empty calories.
Personally, I can't make the trail miles unless my nutrition is good. My junkfood-backpacking days are all behind me. I should have also brought glucosamine& chondroitin, for that matter. By the end of the second week, I was definately hurting for lack of it.
I've hiked the AT, PCT 3 times, the JMT, and the CDT.
AT: lots of whole grains, dried fruit, etc. Went well.
PCT first time: 50/50 mix of junk food and "nutritious" food. Went well.
PCT second time: pretty much 100% junk food like ramen, Lipton dinners, box mac-n-cheese, candy bars, and 2lb value packs of cheap sandwich cookies. I had very limited resources for this hike. Went well.
JMT: First hike with Swipe (then GF). Ate really well, but this is a much shorter hike and we did fewer miles per day. Hard to tell much difference re: diet. Only hike I've ever brought way too much food. I planned to eat like a thru-hiker, but with only 2 weeks my thru-hiker metabolism didn't seem to wake up.
CDT: By this point we're married. Physically, a very hard hike compared to the others. Swipe got tired of budget/dirtbag food and we ended up switching abruptly mid-hike to a much better diet. More tasty, literally 3x more expensive to resupply. Went well before and after the switch.
PCT third time: at her insistence, we ate very little junk food. Went well.
At home, we've always eaten a rather healthy, nutritious diet of whole grains, fresh fruits and veggies, and low in animal products and refined sugars. I know that these foods are "better" for you in the long run. However, on the trail, doing 20-30+ miles per day for months on end, I've never noticed any performance difference between eating junk and eating $$$/well, with or without supplements. YMMV. For example, my wife may certainly have been physiologically tired of junk food on the CDT, but I suspect that the real reason was that she was ideologically/culturally ashamed and guilty -- perhaps subconsciously -- to be eating "white trash food".
The only nutritional variable I've noticed is calories: when I have more of them, I hike strong. When I have fewer of them, I hike weak and get cold. I can't hike on skimpy amounts of
any sort of calories, whether nutritious or empty.
+1 on the glucosamine/chrondriotin. I know that the credible research says that it's snake oil, but it sure seems to help.