Everything depends quite a bit on the hike conditions...pace, duration... at more intense multi-hour pace don't reach for various sandwiches with such and such salamis, possibly with mayo and fatty cheese...!!! enjoy as many small energy-rich meals as possible...sandwiches with jam, energy bars, energy gels, and isotonic drinks. Two to three days before exertion eat protein meals and lots of water....on multi-day exertion protein meals only before longer rest...evening... Just before exertion, and occasionally during, it's recommended to take BCAA amino acids, to prevent muscle breakdown and as additional energy for muscles.....OF COURSE all this doesn't help if we are not previously properly fitness-prepared....and lots of enjoyment....