Calories per day formula

[JAK]

I can hike a long day also, but I definitely slow down after a few hours. If I stop and rest and have a snack I can pick up the pace again. I am not sure I could maintain 550 per hour for 12 hours unless I was highly motivated, and then I don't think I could maintain it over multiple days. Plus there is the tree factor, which I recently discovered, which is that you are more likely to trip and bump your head on a tree or rock as the days and hours progress.

8726 calories per day seems very high to me unless you are really hauling ass.

[JAK]

So I think some might use a 4 modifier, but most maybe 3, or even 2. So it depends. My last hike I was carrying 20 pounds skin out on my 220 pound body, and averaged 12-15 mile days over 8-12 hours with moderate terrain, and burned 0.5 pounds of food per day plus about 1 pound of body fat, so about 4400 calories per day, compared to my basal metabolism of 2000 or 2200, so a modifier for me of about 2.0 to 2.2 .

[JAK]

With more severe terrain, like the Fundy Footpath with lots of ups and downs, I the modifier would be closer to 3.0 for a 8-12 hour day. So 2.0 to 3.0, for me.

[LDog]

My guess would be that during an activity, it is only the physics of the activity that matter, which would only be concerned with a person's weight. An analogy could be made to how much force it takes to move a lever, regardless of the composition of the lever, that sort of thing.

A BMR, in contrast, does depend upon age, as younger people tend to have a higher resting metabolism than those with more experience under their belts.

I would still think it would include height, though.

Back to your original question, as to what the modifier would be for a person hiking 12 hours a day, if we assumed that (for me), an hour of hiking burned 550 calories, a 12 hour day would burn 6600 additional calories.

Given that my BMR is 1772, and a base state Harris-Benedict modifier of 1.2 gives 2126 calories per day to maintain my weight, my total for day of hiking 12 hours at 550 calories per hour would be 8726, which would yield a Harris-Benedict modifier of about 4 if my math is correct.

I found this in Conditioning for Outdoor Fitness in Google books:

http://books.google.com/books?id=ctm...EwAw#v=onepage

They use a similar formula to determine what they call a resting metabolic rate. Then later say (paraphrasing):

A 40 yo, 5'9", 166 lb male has an RMR=1671. With a 44 lb pack, hiking 8hrs/day in the mountains, w/2 hrs of breaks, he adds a caloric requirement of 600 kcals/hr, times 6 hrs, for 3600 additional calories over RMR, or a total of 5271/day

I plugged that into my spreadsheet I came up with a factor of 2.7 - for an eight hour day with six hours of walking ... A ten hour day would be a bigger factor based on the above info ...

So, to get to your point, instead of using the multipliers, one might add "Hours Hiking" times 600 k/cal to the BMR (hrs * 600 + BMR) for an estimate.

Here's the spreadsheet I've been playing with. Still trying to figure out best way to separate pack weight from BMR



Cheers

[Jonnycat]

So, to get to your point, instead of using the multipliers, one might add "Hours Hiking" times 600 k/cal to the BMR (hrs * 600 + BMR) for an estimate.

I like your method, Willy, it makes even more sense. It would also allow a modification of the calories burned per hour, depending, as JAK brought up, upon one's level of exertion during the time spend actively hiking.

[chasegru]

So, to get to your point, instead of using the multipliers, one might add "Hours Hiking" times 600 k/cal to the BMR (hrs * 600 + BMR) for an estimate.
Here's the spreadsheet I've been playing with. Still trying to figure out best way to separate pack weight from BMR

I prefer to use miles hiked and elevation gained and add that to BMR:

Far as seperating pack weight from BMR...there's an app for that...

[SassyWindsor]

I never worry about calories while on a hike. It's when I STOP hiking that calorie management becomes a headache. I have never, NEVER, come off a hike and had a weight gain and I can't remember any of my hiking friends complaining about gaining weight during a hike.

[JAK]

I only worl calories during a hiking because I am trying to use them to maximize weight loss, without bumping into trees and falling off cliffs. If I was thinner I would worry less.

[JAK]

Sorry for all the posts. On my last hike I think I was successful in determining that I can get away with as little as 0.5 pounds per day, and still hike a full day, but I am not sure yet that it will work on the Fundy Footpath where I know I can burn more calories per day because of all the uphills and downhills, but it does take more carbs, not just more body fat. I think I confirmed for myself I can only burn about 1 pound of fat per day while hiking. As I thin out it will be less than that, but for now I have about 65-70 pounds of body fat. I think 1% of your body fat per day is a good rule of thumb, but while hiking you can burn more on long slow days. I might use 2% of my EXCESS body fat as my rule of thumb. I figure I have 50 pounds of excess, so 1 pound per day if I hike 10 hours or more. If I get down to say, 10 pounds excess, I will only count on 0.2 pounds per day from my fat stores, and will add some fat to my diet. For now my hiking diet is mostly carbs and protien, even though I burn mostly fat.

[SassyWindsor]

I've met a couple of hikers who were hiking to lose weight. The biggest problem they were having was not eating enough to keep up strength and they were also getting dehydrated easily. I also sensed they were not really enjoying their hike, but this could have been due to some underlying health problems.

[aaronthebugbuffet]

Here's an interesting read about 3 formulas for calorie calculation and macro nutrient ratios.
http://forum.bodybuilding.com/showth...hp?t=121703981

[ScottP]

Eat healthy foods and let your body tell you what to do. If you consistently have odd cravings you're probably missing something important.

there's just so many factors that come into play

age, weight, height, etc.
temperature
miles hiked
elevation gain
terrain
pack weight
shoe weight
stride efficiency
fat stores used
etc.

[LDog]

Far as seperating pack weight from BMR...there's an app for that...

Is that an iPhone app? I couldn't tell from the web site.

[chasegru]

Is that an iPhone app? I couldn't tell from the web site.

It an old school PC app--getting an iPhone app developer proved a bit too difficult.