In the summer in the Rockies, fresh bagels and cheese will keep for about three, maybe four days without refrigeration. After that, they become possible sources for exciting new antibiotics. To avoid becoming guinea pigs on the fourth day, we often substitute crackers for the bagel and a small can of meat for the cheese. Sugary foods are easy to bring backpacking, since they're compact and keep well, but Cora and I find that the sweetness becomes sickening if we bring too much, even though we both have a sweet tooth the size of a saber-tooth tiger's. Non-sweet foods that crunch are often in high demand in the backcountry, which is why we usually bring crackers. Eventually, of course, these brittle snack items crumble into bird food, but they're still quite palatable if you change your attitude. Simply decide that what you really wanted all along is croutons, and sprinkle them on your pasta or rice. These snacks are bulky, but not heavy in comparison to their caloric content, and they have a side benefit: They make your pack look enormous, which encourages impressionable tourists to make laudatory comments on the trail. (Of course, you have to ignore the scorn of modern-day John Muirs who are out for a week with a pack no bigger than a baguette.)
When I was guiding expeditions on Mt. McKinley, I found that most people quickly decided that hot cereal was about as appealing as snail slime. Perhaps the texture began to seem a little too glutinous to stomachs already unsettled by the altitude and enormous exertion; at any rate, I remember cooking gallons of oatmeal and cream of wheat and seeing a few tablespoons disappear reluctantly into people's mouths. Cold cereal can always be made hot, if so desired, but the opposite is not true. People also quickly rejected excessively fatty food, such as salami, because it upset their stomachs when they began laboring uphill again after lunch. The candy bars everyone lapped up eagerly during the first few days also became tiresome quickly. One climber commented to me after a week on the glacier, "I don't want to see another Milky Way bar as long as I live." The foods that did retain their appeal were what I call "real food." Cold cereal always tasted good for breakfast. Mildly sweet logan bread for lunch never palled. A bagel, carefully thawed, then buttered, always went down well, as did a dinner glop richly reinforced with cheese and butter.
For the last several years I’ve been carrying a high-end sports drink like Cytomax (my current favorite) in a bottle tucked into a holster on my hip belt. That enables me to drink on-the-fly, so I stay better hydrated than if I have to remove my pack to get a drink. By using a sport drink rather than water, I provide an even flow of calories to hard-working muscles. Staying well-hydrated and well-fueled certainly seems to increase my stamina during a long day with a big load. Other backpackers prefer “hydration systems,” usually made of some kind of soft, collapsible bladder with a drinking tube attached. You can stow the bladder in the top pocket of your pack and clip the drinking tube to a shoulder strap for easy access while hiking. The disadvantages of a hydration system are the ease with which the tube can hang up on branches and the greater difficulty of cleaning a bladder compared to a conventional bottle.
So far, I've only mentioned foods that are readily available in any well-stocked grocery store. One alternative is to buy freeze-dried food from a backpacking shop or mail-order catalog. Freeze-drying is a high-tech method of preserving food that creates a product that can be rehydrated much more satisfactorily than ordinary dehydrated food. Unfortunately, you'll get more pleasure letting the names of the various dishes roll around on your tongue than you will from eating the dishes themselves – and you'll get more pleasure from that than from actually eating the food. Supermarket foods are generally much less expensive than freeze-dried food and they can be just as tasty. The real key to enjoying backpacking food is variety, not expense. When I was helping guide an expedition on 22,834-foot Aconcagua, the highest peak in the Western Hemisphere, we brought a large number of Alpine Aire freeze-dried dinners because everyone had eaten so many Mountain House dinners on previous trips that they were heartily sick of them. Given a choice at the beginning of the trip, everyone immediately grabbed for the Alpine Aire dinners. After a couple of weeks of Alpine Aire, however, everyone suddenly decided that a Mountain House dinner would be a delectable feast.
Despite all the flack I've given freeze-dried food, I must admit that I brought it for all of my expeditions to Alaska. The reason? Convenience. With most freeze-dried food, you simply add boiling water to the foil pouch and let it sit for five or 10 minutes. There's no need to stir the glop to keep it from burning, no pot to clean and you can be heating the water for your cup of cocoa while you eat your dinner – or, as we always did in Alaska, you can be melting more snow, an interminable task during high-altitude Arctic trips.