steelfrog, I wrestled with this same question last year and found that I got a wide range of caloric burn estimates depending on which resource I used. I'm 175 and the basic number I accepted as an average was about 500 calories per hour, assuming a 10 pound pack on reasonably level terrain below 5000 feet. Pack weight, hiking speed, elevation gain and altitude all play a role in that burn, along with things like body mass index, but I've yet to find a resource that takes these things into consideration and can spit out a truly personalized number.
When I use these on-line calculators, I play around with my body weight to simulate varying pack weights. Adding 30 pounds to my weight, I typically get about another 100 calories per hour burned. Almost all of my hiking is done in mountainous terrain with elevation gain as the goal, so I thumbnail another 100 calories/hour for that during the significant uphills (pure conjecture - it's probably more). In the scheme of things, I don't think there's much you can do to burn calories faster than strapping a pack on and heading uphill at a good pace. As I recall, a person burns between 75 and 100 calories per hour when at rest and something like 250/hour walking.
Net result, hiking steadily up a challenging grade with a 30 pound pack for an hour, I guestimate about 700 cals burned at the extreme top-end, 600 with a daypack. Add elevation in and I'm sure it goes up noticeably, but I don't know how to quantify it. With the difference in our body weights, I would suspect a bit more for you. I once had a sports science major tell me that something on the order of 900-1000 calories burned per hour is about the max the average human body can handle before very rapid exhaustion sets in. The past two years when I've made my Sierra trips, I'll generally lose 8-10 pounds over the course of a week hiking above 10K'. That includes a Whitney hike each time as well - and that's eating pretty much everything Doug can throw on the grill, with no dietary restrictions.
Maybe Harvey and Ken will weigh in (pun intended) - being physicians who mountaineer, they probably have some good solid data that can be relied upon.
