i was with a guide only in the sense that I was there with someone that had done it before. It was easy to know when you were supposed to stop each day because it was the only signs of civilization anywhere. Some days were longer than others!
I was quite overweight when i went and also had pretty terrible eating habits back then. When pizza and beer me was introduced to lentils and rice as well as 5+ hours a day of exercise, the kg's just fell off of me :)
It sounds like a wonderful adventure and a great way to diet!