Calories per mile
Any idea or do you know of a chart that has a good estimate of calories we burn per mile with pack weights?
An interesting topic with variables that number in the dozens. In the 70s the military spent some time on this issue to determine how much energy is expended in carrying various loads over different terrain using something called the Pandolf Equation. It involves math I don't pretend to understand, Outside Magazine ran a article on this https://www.outsideonline.com/outdoo...rie-estimator/ that provides some graphs many have found useful.
Given the variables, this is about the closest thing I have ever seen of a "standard" estimation of expending energy and related caloric burn.
From a practical standpoint, more than you can carry (unless you are Tipi Walter) and have anything else in your pack. Fat has 9 cals per gram, vs 4 for carbs and protein. But try eating almost all nuts like I did at the start of my thru and you quickly find there is some limit as to how far you can push that. If you can keep your cals/oz around 150 in aggregate I think that is pretty good. HYOH and YMMV.
Many years ago I came up with my own estimate. At the time I was a member of a gym so had access to equipment (ellipticals, stairmasters, etc.) that reported calories burned. I compared how I felt after a hike with varying loads. I found online charts of calories burned for various activities and time periods. I read the 'average' man burns about 100 calories per mile. Average being defined as 165 pound male. The average female burns about 80 calories per mile, the average here being defined as 130 pounds. This is actually about the same rate. It doesn't matter if one is walking, jogging, or running. Of course running will burn more calories per time period but only because the distance is covered faster.
I put all that together and came up with my estimate:
Carrying 1% of bodyweight burns about an extra 5% of calories. So 1x5.
If Mr. Average carries a 16.5 pound pack (10% of body weight), he burns about 150 (50% increase, or 10x5) calories per mile.
If Mr. Average carries a 33 pound pack (20% of body weight), he burns about 200 (100% increase, or 20x5) calories per mile.
If we accept the RDA of the average man needing about 2000 calories per day and we add in a 10 mile hike with a 33 pound pack, we're looking at about 4000 calories per day.
This is what I came up with, it works pretty well for me, and I believe it close enough for planning purposes. I am sure there are individual differences. I am perfectly OK if anyone wishes to disagree.
There's some interesting research that shows that the body's base metabolic rate (the energy required to just keep things running at idle) is substantial, and actually decreases when we exercise. See the book "Burn" by Herman Pontzer. That's upsetting to us armchair engineers who look at it as a simple machine. It also explains why it's so so difficult for so many to lose weight by exercising. The book makes mention of AT thru-hikers, too. For a condensed version, there's an interview with the author in last week's "Ologies" podcast.
This paper cites data that carrying a load equal to 20% of body weight increased the rate of energy consumption by 20% . However they found that African women can carry loads on the top of the head over level ground equal to 20% of their body weight with no extra energy expenditure.
https://pubmed.ncbi.nlm.nih.gov/3951538/
I'm not sure if pack weight is considered but on my last overnight trip I used the Fitness app on my iPhone. After hiking 5.8 miles and about 1100ft of elevation it showed 15,939 steps,20 flights of stairs and 1,632 calories burned.This was at my lunch break and I hiked 5 more miles to my evac point.
Sleep on the ground, rise with the sun and hike with the wind....
Moderators, if I'm too much astray from Straightforward, please delete. Anyone else, I offer this response as part of the discussion, not to simply argue.
I disagree with this premise and I think it is fairly simple to disprove. Consider how you feel after walking 1 mile without a pack. Consider how you feel walking 1.2 miles without a pack, or 20% further so 20% more calories (which is a measure of energy). Consider how you feel walking 1 mile with 20% of your bodyweight. I believe we will all agree walking 1 mile with 20% of bodyweight requires more energy than walking 1.2 miles without a pack.Originally Posted by Odd Man Out
As for the head-carrying women, I do not have the knowledge or experience to offer an opinion or explanation.
I should have mentioned that I live in Florida so don't factor in elevation changes. I will assume your pack was about 20% of your bodyweight as that is probably close, so without factoring in elevation, by my estimate 6 miles is roughly 1200 calories. Your app suggested 1600. My experience with apps I have used is they typically estimate more than I do. So factor an optimistic calculation and factor in elevation, and it is probably not too different than my estimate.
I have seen time estimates for hiking that do factor in elevation, but I don't recall what they are. Perhaps the difference in time required to hike a distance flat vs elevation could be used to estimate the difference in caloric needs.
This is similar to what I was taught in the Army Master Fitness Trainer School. However, the caloric/energy difference per mile needed isn't really sex dependent. Note they change the "weight" of the average female. But physics is physics and the energy required to move 165 pounds 1 mile has no relationship to the sex of the individual doing it. Just wanted to point that out to anyone who gets confused by that point. In my 20+ years as a personal trainer I just told individuals to "credit themselves" with 100 calories for every mile covered on foot and half that on a bicycle. Yes, a much larger person is going to burn more as they have more mass to move but I won't get into that here.
Gradient does have a slight effect on the amount of energy needed as well but just slight. Remember, most of us are going to hike downhill as much as we hike uphill over the course of our hikes and the downhill will require less energy as we have the assistance of gravity.
I would reject the RDAs recommendation of 2000 calories per day for the "average man" as first off, that's based on old data. And I also don't think you can just flatly add 2000 calories to it, the original 2000 being more the problem. The RDA was based on what people's activity levels were back when that number was established. That included a lot more walking daily, and other physical labor, than what is currently done. It also includes the energy needed for basic physiological functions which are not actually based on activity level. That being said, your 4000 per day is working for you so stick with it. And it's a good enough starting off point for others.
I would really love to see how anyone packs that many calories per day. I eat completely differently than most people do so I can't imagine 4000 calories a day of mostly processed foods.
https://tinyurl.com/MyFDresults
A vigorous five-mile walk will do more good for an unhappy but otherwise healthy adult than all the medicine and psychology in the world. ~Paul Dudley White
fitness apps are very flawed. They are based off formulas that only appear to be individualized if you are able to enter your weight and other factors. I wonder if you did that same exact trip but changed your weight to include the starting weight of your pack, what the calorie burn would show.
Maybe I should do something like that myself. After all, I love tracking numbers!
https://tinyurl.com/MyFDresults
A vigorous five-mile walk will do more good for an unhappy but otherwise healthy adult than all the medicine and psychology in the world. ~Paul Dudley White
Here are some numbers from my fitness app (Map my Run).
This morning I walked 2.33 miles (my neighborhood) with a 20-pound pack. My estimate is about 300 calories. My app estimates 431 calories.
Last week I did a local trail called the Torreya Challenge. As far as north Florida goes, it's a fairly challenging hike. I wore a 35-pound pack and covered 7.75 miles. My estimate is 1550 calories. The app estimated 1700 calories.
I'm looking at the app and it appears I have entered my gender, height, and weight. I don't see an option for added pack weight. Of course the app is just a tool (it does a reasonable job at calculating distance), and my estimates are just estimates. This may already be more information than the OP is interested in.
I actually carry closer to 3000 calories per day when backpacking and plan to drop a couple pounds of body fat for a 5 day trip. I am not really overweight but can certainly spare a couple pounds.
Last edited by perrymk; 02-16-2024 at 10:25.
I would be very surprised if the app is estimating correctly. Seems WAY too high.
https://tinyurl.com/MyFDresults
A vigorous five-mile walk will do more good for an unhappy but otherwise healthy adult than all the medicine and psychology in the world. ~Paul Dudley White
On my AT hike and other thru hikes, I carried two pounds of food per day max. I tried to get 4000 kcal in there (125 kcal/oz), but even with a lot of fatty, minimally processed foods like nuts and nut butters (I'm vegan, but flexible in trail towns) I doubt I made it. But it was enough--weight loss was minimal (I started lean) and I felt good. I hiked the AT in 106 days.
Of course, trail towns supplied a huge calorie boost, especially in the mid-Atlantic, on the "diner-a-day" tour. And the half gallon challenge. I lost some weight in the South, gained it back again in the North.
"Throw a loaf of bread and a pound of tea in an old sack and jump over the back fence." John Muir on expedition planning
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