MRE's... The left over plastic and trash from those things weighs more than other food alternatives.

If you must have 'heat and eat', here's what the Red Cross is passing out these days. They are pretty good and are about the size of a TV dinner.
http://www.heatermeals.com/

Like Phat and Jak, most of us use grocery store dried, fresh, and packaged foods.
In fact, the last "freeze dried Mountain House" style meal I had was about ten years ago. Those are good for a day or two and you don't have time to make a grocery store run. Instead, learn to pack fresh vegetables, dried veg. and fruits, the new packaged meats...tuna-chicken-beef, pasta's, cereals, etc. It's much cheaper, better tasting, and lighter. Plus, you can make your own nutritional choices.

Sarbar, our own trail chef <img src="/forums/images/graemlins/grin.gif" alt="" /> <img src="/forums/images/graemlins/grin.gif" alt="" />, has an excellent backpacking foods website. Give it a visit.....
http://www.trailcooking.com