Summer solstice is well behind us, which to the outdoorsman means simply one thing, the days are getting shorter and hunting season is fast approaching. Every one of us is now watching gear guides, doing practice runs with our packs, shooting our guns and bows, and we can taste the crisp air of the outdoors in our sleep.
As we start to break down our hunts in the gear that we will take with us, one of the things that often gets overlooked is the food that you are going to take on these long treks up the mountain. No, we’re not here to talk about food at the moment, we are here to get a better understanding of how many calories our bodies ACTUALLY use throughout the day during these excursions, so that we can pack he food we need to keep us performing at our best in the woods.
In all of our research across the hunting and outdoor industry, and through all the gear guide videos that we have watched, it is apparent to us that very few really understand the amount of calories that our bodies burn in these conditions. Many people go through and guess how many miles they are going to walk over the course of a day, and then guess at maybe a couple hundred calories a mile and try to come up with an idea of a few thousand calories to take per day. Then by day 3 you’re wondering why you’re so exhausted. Why you’re so sore? To put it as blunt as possible, it’s because you’ve burned significantly more calories than you thought, and you were not replenishing your body with the food it needs to continue to go at the pace in which you started.
What do I mean by all of that?
Our bodies burn a lot of calories during these scouting and hunting trips, and there are a dozen variables that need to be reviewed to figure out just how much you need to eat to fuel your body properly for these adventures. These variables include things such as your basic metabolic rate (BMR), the speed at which you’re moving, the type of ground you are moving across, the distance at which are traveling, the temperature, and the weight of the pack on your back. To try to keep this as simple as possible, we will section this individually, and add links back to pages to calculate your own calorie expenditure.
Basic Metabolic Rate
When people are pushing out gear guides across YouTube and websites, the thing it seems people fail to factor in the most, is their Basic Metabolic Rate (BMR), which is the number of calories that your body burns on a daily basis just to live. On average, a 160lb individual of average structure, will burn between 1500 and 1700 calories per day just eating and breathing, and moving around in their daily activities. We all burn these calories and yet somehow almost no one factors these calories in when they show their gear guides for their trips. (Not sure where your BMR is, click HEREto use the calculator we use).
Exercise & Hiking
After reviewing several different studies, the average 160lb male will burn roughly 850+ calories per hour when running at a speed of 8 miles per hour. The studies found that hiking burns roughly half that amount without a pack on and on a reasonable trail. If we break that down, that means you are burning roughly 425 calories per hour on a simple trail hike, with no pack, and this is in addition to the calories your body burns just to stay alive!
According to Livestrong.org, a light pack that you might wear on a day hunt would burn 50 to 100 more calories per hour throughout the day. We will go even farther and say that number is closer to the 100 mark or above because we all carry a weapon on these hunts as well. If you are following the math here, when out on your day hunt with your weapon and light pack, on an average trail, you are burning roughly 600 calories per hour including your BMR! When you calculate in a heavier pack for multiple day backcountry hunts, you can burn 200-300 more calories per hour as you go...
Trail and Grade
One factor that has not been included into the equation above is the type of trail you are on and the angles at which you are hiking. This is extremely important because this will adjust your pace, use more muscles, and put the calorie burning into overdrive. If you’re hiking on a rugged trail, climbing over deadfall, dealing with sand or rock, you will have increasing use of the muscles around your knees and other joints to keep you balanced. Each flex of the muscle burns calories. When you factor in the angles/grade you’re hiking, all hell breaks loose.
Now we don’t want to make this a math class so the easiest way to get a super rough estimate of what’s going on we have to reference the United States Military. In the 1970s, the military developed the Pandolf Equation, to calculate how many calories you’re burning as a function of your weight, pack weight, hiking speed, the slope, and the nature of the terrain. Many researchers have broken down this equation and have proved that it will often underestimate the true number but it will be good enough for a rough estimate for us.
The one thing we noticed when messing around with this equation is that a 1% increase in the slope you are traveling can increase the amount of calories you burn a ton. The second thing is that it also breaks down the calories burned by mile instead of per hour, but does not factor in your BMR. This is very important to us as outdoorsmen because let’s face it, we are for sure going to take a LOT of breaks when hiking back into the remote country, and a per hour burn rate isn’t actually going to be relevant to us. (We will get to examples and links at the bottom for you to go and calculate your own rates).
To actually know the exact number of calories you burn is going to change from one person to the next. Type of pack, load distribution, age, fitness level, gender, the weight of your boots (One pound on the foot equals Five on the back), and more all play factors here. Men burn calories faster than women due to a higher muscle to fat ratio. The variables are endless and you need a college degree in this stuff to actually understand it. That’s not what we are trying to do so lets break it down based on my personal calculations.
When my September hunt hits, I will stand at 6 ft tall and roughly 195 lbs, and around 10% bodyfat. My calculations based on fitness level state that my BMR has me burning around 2,100 calories a day just surviving. By reviewing my tracked hikes from my Garmin from previous years, I see that when moving, I move at a speed of around 3.6 mph, and I hike roughly 6-10 miles per day.. I can then scroll through the Outside Analytics maps to see the average slope percentage that I am hiking to be around 20%-25%. We recently wrapped up a gear guide and my day pack is roughly 45lbs, and my pack weight when I head in for 4-5 days is around 70 lbs. If we gather that data and enter it into the Pandolf Equation HERE, I will just use the gravel road setting although that will underestimate my burn rate, the input reads that I will burn 564 calories per mile with my day pack and 611 calories per mile on the trek in to spike camp!
Say it was a long day on the mountain and I covered 10 miles that day. If we don’t calculate any other movements except the hiking, I will have burned 5,640 calories just hiking around! Add in my BMR and my total calories burned that day are roughly 7,740 calories!!!!! That is not uncommon either.
Now just for fun lets consider that the terrain is closer to ‘sand” and not a gravel road due to deadfall, heavy brush, and so on. Then lets cut the slope to 20% from 22.5%, and the miles traveled down to 7 from 10. This equation has me personally burning 842 calories per mile. The numbers come out to 7,994 calories in a single day and I can guarantee you it is actually much higher if you consider setting camp, loading the pack, getting up and down to glass and so much more.
First of all, what an eye opener right? One of the gear guides we reviewed before writing this had an average male packing 2,800 calories per day into his pack for a 5 day hunt into sheep country. It is safe to say after doing the calculations that he needs more than double that.
Really what we want you to take away from all of this is that when day three or four hits, and you are flat out exhausted, it directly correlates to the amount of calories you are consuming compared to how many calories you are burning. Now my example is on the extreme side but regardless, I can promise you that you aren’t eating enough. At that point it doesn’t matter what type of calories you are consuming, just EAT!
*By: Jeff Moran (@relentlesshntr)