Breakfast
Oatmeal is a hearty and nutritious way to start the day. If you don't mind the cooking time, regular slow-cooked oats are fine, but if you want to save time and cooking fuel, go with instant oatmeal, which come in single-serving packets, so they're easy to pack and use. Add some powdered milk for an extra shot of flavor and nutritional benefit.
If you don't want to cook, granola or a dense multi-grain cereal can be mixed with powdered milk. This has the added benefit of being great for snacking, too.
Lunch
If you're trying to put some miles in, you don't want to tarry long during lunch. One of the easiest and fastest lunches is peanut butter on a tortilla or pita. Peanut butter has high caloric value and plenty of protein and fats. Plus, it'll keep well in almost any conditions.
For a change of pace, try slicing some pepperoni and cheese for your pita or tortilla. A hard cheese, such as cheddar, will hold up well on the trail, and cured meats are packed with protein--something your body will crave after a few days of lugging your pack.
Dinner
You probably have a little more time to kick back and cook a meal at dinner. A solid standby on the trail is packaged noodle meals. These are usually sold in packets at the store to use as side dishes. Cooked in boiling water, they make a hot and hearty meal. Add a vacuum-packed pouch of tuna, salmon or chicken for a square meal.
Snacks
Snacking on the trail is a great way to add a little variety to your diet and keep your energy level up. The old trail standby of GORP (good old raisins and peanuts) is favorite, and you can experiment with your own variations by visiting the bulk-food section of your local market. If you want to save time, there are plenty of commercial trail mixes on the market.
Many hikers swear by dried fruits, which add some natural sugar into the diet and satisfy your sweet tooth. Consider nuts as well; they're easy to carry and have plenty of calories to replace the fuel you're burning.