Check out: TrailCooking.com
The owner, Sarbar, often posts on this site. There are a ton of recipes on that website. Many of them use standard supermarket ingredients, and require only boiling water to prepare on the trail. You can prepare them in the pot--add to pot when water boils, remove from heat, let sit in a cozy. Another method, which I use, is to package the dry ingredients in freezer bags, add boiling water, set in a cozy (or wrap in a coat or hat) for 10-15 minutes, then enjoy. The one caveat is that the cooking time for whatever you buy should have a cooking time of 10 minutes or less. With the freezer bag method, no dishes to wash except the spoon. Can you tell that I hate washing dishes?

Packit Gourmet is a good source of bulk freeze-dried ingredients. I use their meats and a few of their vegetables, although most of my meals are home-dehydrated. (Peas, in particular, do not do well in dehydrating--they remain the consistency of buckshot after cooking.) They also do meals as well as bulk ingredients.

If you want to lose weight, no worries once you get started on your thru-hike! The only problem comes after the hike is over, you still have the thru-hiker appetite but are no longer burning that enormous amount of calories every day!