@Tom: I don't claim that I'm right and you're wrong. I don't claim that my experience on 3-day trips is valid for longer trips. I'm simply claiming that there are half a dozen uncontrolled variables here (trip length being one of them), and since you can't account for them, you're just spinning your wheels by trying to calculate things theoretically.
Rod wrote: "It seems a bit light, but correlates fairly well with my experience of the first couple of days of a walk, when my appetite often falls off. I'm wondering how you determine that you don't rack up a large calorie debt over those couple of days."
I think it's very difficult, outside the context of a experimental physiology ward, for anyone to know in any quantitative detail what anyone's metabolism is doing. But it seems to me that if my body was burning 4000 cal/day for three days, and I was only eating 2000 cal/day, then I'd probably get hungry as hell. Ask any dieter — your body doesn't just start burning fat without sending your brain some pretty strong hunger signals.
"Is your 2000 cal consistent with what you use in non-BP life?"
I've never counted calories in ordinary life, so I really don't know. I'm a small, skinny guy, so I probably burn less calories than most adult males.
I just spent the morning assembling my resupply shipment for the second half of the JMT, and I learned something that may be relevant here. On previous trips, my diets has been more heavily weighted toward fats. For this package, I restricted myself to proportions of 50-35-15 for calories from carbs, fat, and protein, and this resulted in significantly different food choices than what I normally bring. I have a lot more jerky and granola, a lot less nuts. (I go no-cook.) Since nuts are more energy dense than jerky and granola, the result was to cut the energy density of my food by about 20%.
I'm 140 lb, so I also eat less than most adult males.
These two factors may help to explain why I've typically felt fully satiated with about 1 lb/day of food, whereas a lot of people apparently eat 2 lb/day. I have definitely noticed that when I go backpacking with my father and brother, they eat amounts of food that seem just completely nauseating to me, even taking into account that they both outmass me.
Another uncontrolled variable that probably makes comparisons difficult is that people tend to eat a lot of food immediately before a trip ("Ah, my last real food!") and immediately after ("Hell, I don't want to eat more granola now — I'm having pizza and beer later today!"). Personally I've also included some luxury food in my resupply package that I'll eat immediately rather than packing it out. This is potentially a huge confounding factor.
Dan wrote: "I am 5'7'' and 155lbs and my friend is about 5'10'' and about the same weight. The hiking we are doing will b strenuous, but not crazy. Half the trail will be half off trail, with a few passes mixed in. We only do MAX 10 miles a day cause we like to get alot of fishing in. BAsed on that….how many calories do you think we would be burning??"
Well, it seems clear that my numbers are at the very low end of the range, so it seems to me that we can set a pretty good lower limit. Your body mass is 11% higher than mine, and I eat 2100 cal/day on short trips that aren't very strenuous, so a bare minimum for you would seem to be 2300 cal/day. (This is assuming that you catch zero fish — which I hope won't be the case :-) On the high end, I hear people talking about figures like 5000 cal/day. That doesn't help to narrow it down much, does it? Do you have any data at all on how much you've eaten on past trips? Even if it was just "I went through a Garcia in 7 days," that would give us at least something to go on.