A few things/rules to think about:
1) All the food you put inside your pack should weigh at least 100 calories per ounce (or more)
2) Just because you don't feel hungry on a mountain hunt, doesn't mean you shouldn't be eating anyway! You're body needs to replenish and rebuild and food/water/sleep is what makes that happen. Water is the same way; just because you're not thirsty, doesn't mean you stop drinking....that usually results in death.
3) You CAN get away with a very low caloric intake on a backpack hunt, but you'll be running on barrowed time and most don't know when that time will run out. So if you crap out on day 5 of a 10 day hunt, was saving a few ounces a day worth it?
4) Even a 3,500 calorie per day meal plan won't get you half enough caloric intake on a tough backpack hunt and you can expect to burn over 4,500+ per day and double that if you're really getting after it. So the guys that are bringing 1,500 per day are probably also loosing 1-3 on their own body weight each day too....not healthy
NOTE: A backpack hunt is not the place to go on a diet or test the waters of food depravation. You've spent a lot of money on gear and tags, so WHY risk starving yourself to save a little weight?
Good luck this season!