I have to echo some of the others -- a backpacking trip is no time to be dieting. If you are overnighting, you are carrying a pack of at least 30 pounds, plus covering 10 miles per day, thus burning at LEAST a couple thousand extra calories. You've got to keep your energy up, or you won't have a good time of it. I did a ton of hiking and backpacking last year, and ate a lot more than usual, and didn't gain a thing.
Here are a few suggestions:
-- Quaker "weight control" instant oatmeal has higher protein and less sugar. I'm a big fan of oatmeal for breakfast and any time. You do need the carbs.
-- PB2 powdered peanut butter has 85% less fat, but all of the protein. You have to mail order it though, and it might be a bit of a hassle to mix up with water. You can buy it at
www.bellplantation.com. You can spread it on low carb tortillas and make wraps. Or take whole wheat bagels or pita bread, they'll keep for a few days. Frankly though, regular PB is probably better, you need the fat calories as a source of energy, it is satisfying and will sustain you longer.
-- I usually do the freeze-dried prepackaged backpack foods for dinner, but you could split with someone else to cut calories. You have to think of convenience too! (and pack weight)
-- protein bars (like Atkins) are calorie-controlled and portable, but watch for those that may melt.
-- when day hiking, I take carrots and apples. They would keep for a few days. Bananas don't keep more than a day in your pack, take my word for it.
-- also: instant soup, sugar free hot cocoa, sugar free instant international foods coffees (for the coffee addict like me). Crystal light packets offer a nice change of pace from water without all of the calories of gatorade.
You can order the freeze-dried entrees online ahead of time and check out the calorie counts. Some of them aren't as bad as you think -- for example, the chili mac with beef is 270 calories per serving (half of the 2 serving packet). They have breakfast foods and freeze dried fruits too.
For another source of freeze-dried fruit, check out the baby food aisle in your supermarket. Seriously!! Gerber's graduates line has fruit and veggie "puffs" that are just freeze dried fruit and veggies. Low cal, light, and portable.
I tend to avoid the trail mix because I can scarf down 1000 calories real easy. But jerky is great -- there are things like turkey jerkey now that are high protein and lower fat.