Mre's are really heavy. The law requires the military to be able to have a certain amount of calories per day.
If you don't plan to be out in the woods for more than 6 to longer days at a set, think Lipton meals. You can get them at your local grocer for less than 2$ a packet. They are light, and full of the carbo's you need to sustain yourself during this time. I've done some extremed packing/hunting trips with these things and have come out full. Augment them with protein bars and energy bars, you'll be good to go.