fats vs carbs
I just wanted to chip in with my athletic training advice.
I'm a distance running coach and a former highly trained runner myself, and from my experience, I know that longer distance activities like biking, hiking, and running marathons are 99% aerobic exercise. You may go anaerobic in a sprint at the end or while you are climbing a particularly steep hill, but like I said, most of the time you are in your fat-burning, aerobic mode.
This said, I firmly believe in eating a balanced diet during the day and during exercise. Trans-fatty acids are the only subgroup I would stay away from. In my experience hiking, the best foods to eat are not all sugars/carbs. You see people eating trail mix because it usually contains peanuts, chocolate, raisins, cereal.... a healthy mixture of proteins, fats, and carbs. This will provide you with sustained energy, rather than spiking your glucose level like an all-carb snack would.
If you had a breakfast of bacon, eggs, and pancakes, you would have a far more successful day of hiking than if you had a 2 liter bottle of Coke and dry cereal. My favorite hiking foods are baked beans, Snickers bars, and oatmeal; all are cost-efficient and have surprisingly well-balanced nutritional qualities (energy-wise, at least) although candy bars have trans-fat in them which is bad for heart disease.
As for training, I would recommend one longer run during the week, preferably at a conversational pace over a moderately hilly loop. I would lift weights to build strength in your quads, hamstrings, and calves, as well as your shoulders, arms, and back. It would also be good to mix in 30-45 minutes of steady cardio such as running, elliptical machines, or stairmasters 3 to 4 times per week. Allowing time for recovery is important.
Some other things to consider: hikers are usually sore at the end of the day due to getting beat up on the downhills. Dehydration causes a decrease in recovery time, so drink fluids often. Try to spread out your effort and don't hike so hard as to put yourself into oxygen-debt. 5 smaller meals are better than 3 big ones.
Thanks for listening to my 2 cents.