I am planning on doing the inca Trail later this year which includes 4 days of treking. Food is provided on the trek, but i'm a bit concerned about keeping my sugar levels up when taking into consideration the walking, heat and altitude. Can anyone give me any good ideas on what i can take with me as a supplement. I was thinking something along the lines of Nutrigrain bars, but no idea whether this is the right kind of thing to help, or whether anyone has any alternative ideas. Any ideas would be great.