Nutrition For Mountaineers and High Altitude Hikers

Inside this article, we explore some evidence-backed (and practical) nutrition strategies that an alpinist, mountaineer or hiker can use to perform at their best during a high altitude mountain adventure. 

Article written by Kyle Kamp, registered dietician and founder of Valley To Peak Nutrition.

As many incredible things as there are to behold in this big, beautiful world we're fortunate to live in, I would argue fewer things inspire awe, ambition, and aspiration the way a giant mountain peak does. They're peppered with ridges so jagged they resemble the outline of a shark's mouth more than the granite slabs they are and beckoned to be climbed.

Some take this inspiration to an entirely different level by challenging themselves, their bodies, and their safety to pursue athletic endeavours amongst the tallest of these behemoths.

Many, many years ago, we didn't know much about the nutrition needs of mountain climbers. In fact, researcher SJ Boyle said "little is known about weight loss and changes in body composition at extreme altitudes." as recent as the 19080s(1).

Thankfully, we've come a long way in our research of these athletes in the last 40 years and our understanding of the demands placed on their bodies when performing at high altitudes- things like what affects weight changes, appetite, and more importantly- just how to combat those maladies.  
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Factors Affecting Nutrition
​While At High Altitude​

​There are a variety of factors that affect the overall energy intake of mountain athletes, but all signs seem to point in the same direction: altitude and the harsh environment that exists far, far above sea level.

Generally speaking, the most common explanation for why people tend to lose so much weight and develop so many nutrition-related issues in high-altitude environments is rather simple: acute mountain sickness (AMS) or quite simply just known as altitude sickness. AMS can certainly become a much more serious issue that culminates with fluid accumulation in the lungs and/or brain; however, it can also present a host of problems that are more pests than life-threatening.  

What's more, it is to correct the thinking that AMS happens only on big 5000m peaks. That's not true. There are documented cases of AMS at the lower altitude (3000m or 10K feet) ski resorts in America(2). This is relevant to point out because it's easy to see where a reader's mind would drift yonder to Nepal and Tibet, where the peaks of mountains match the cruising altitude of some jets. This thinking would cause us to miss the larger population of athletes performing ultra-marathons, cross-country ski contests, and climbs at the moderate elevations of the peaks found in the Western US.  

Without further ado, let's look at some factors that cause mountain athletes to be in a negative energy balance when it matters most Spoiler alert: much of this is beyond your control, but we have some potential remedies to consider as well.

High Altitude

Author's note: The literature is full of studies on nutrition and performance "above altitude". The authors are usually referencing an elevation of around 5000m or of 16,404 feet above sea level; however, when referenced here, I am referring to an altitude of anything above 5,280 feet above sea level unless mentioned otherwise.

I've done my best to not bore you with a litany of studies on altitude affecting energy intake, weight loss, loss of lean body mass, etc., as the findings are much of the same. I have highlighted two that seem particularly relevant and paint a realistic picture of how drastic the effects of elevation can be on energy intake in anyone from trained athletes to weekend warriors. 

It's common knowledge for most that our appetite sucks at higher altitudes(3). Some studies have taken the "duh" statement a step further to quantify this with a number. A research by the name of Amellini took a group of climbers (healthy) and tested the number of calories needed at rest and their starting body composition; that is the ratio of fat-to-muscle contained in a person. The group then trekked for 16-days in a high altitude environment.

I'd be willing to bet the group would have expected some changes in appetite, energy intake, and RMR; but I'd be curious to know if they expected the type of changes they found- a 29% reduction in energy intake during high altitude exposure was observed; that's -1,160kcal deficit on a 4,000kcal die (for those who don't feel like getting out their old Texas Instruments calculator). The reduction in energy intake caused an average loss of 3.3kg (7.26lbs for those who still haven't broken out the calculator) over 16 days. 

The issue isn't just the deficit but what the deficit translates into. Of that 3.3kg loss, over 1.1kg of it was muscle loss. And muscle loss, as you can imagine, means reduced strength and/or stamina.. .which means poorer performance...which means a potential summit bid or not.
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Effect on Appetite and Fullness

It's not tough to see where an athlete performing several thousand feet above sea level would struggle to eat. There is a combination of factors that contribute to this, but even hormones aren't immune to the effects of being in an environment that has far less oxygen than what's found at sea level. Research has shown suppressed levels of ghrelin and leptin in folks at high altitudes. 

A 2013 study The 2013 study (5) took a group of people who normally do not live in a high-altitude environment to 11,800 feet (3596m) above sea level. The group stayed there for 48 hours, had their ghrelin (the hormone responsible for hunger) and leptin (hormone responsible for helping with fullness) levels measured, and were then taken up to 14,070 feet above sea level to spend 7 days trekking and climbing.

Their results are quite fascinating:

• They observed a decrease in energy intake of 850kcal/day by the group.
  
• The average total weight loss of the group was 2.12 kg at the higher altitude.
  
• Leptin had a significant increase over normal amounts (54.9%!) at the 48-hour, 11,800-foot mark.
  
• The levels persisted to be elevated through the seven days, and ghrelin decreased by as much as 30% when compared to basal levels.
  

​It's easy to see how the effects of altitude suppress the appetite with these factors are accounted for. ​

Environment and Temperature ​

Most high altitude mountaineers understand they'll be subject to cold temperatures when they agree to an expedition. It's well-known that, on average, temperatures drop significantly as the altitude increases. What many aren't prepared for is what that will do to energy (calorie) needs AND how to bring about a remedy.  

In one study, a group was given activities to perform in the summer months, while a second group was given the same tasks to perform in the winter. Surprising to many, the winter group burned over 500kcal per more in their activities (6).  

Sure, sure, you could argue that participants of the study had different metabolisms, blah, blah, blah, but the heart of the study shows this- your calorie needs are significantly greater in colder environments than in warm environments. And that makes sense if you think about it.

​We have a very efficient system to cool ourselves off through sweat. But no great way to insulate ourselves against the cold temps that can come with climbing. As such, the body uses a tremendous amount of energy to keep itself warm.

Potential Subjective Factors Affecting Intake ​

Let's be honest; it's not comfortable spending several days in an environment that is cold and lacks oxygen.

It hasn't been well-established what the role of this suffer-fest at high altitude plays in whether or not an athlete eats; however, we have also found that the type of food offered can play a big role.

Researchers found when things become a bit more plush (cots with warm down-insulated bags, etc. vs the ground) and palatable food is offered at 15,000 feet, athletes demonstrate adequate calorie intake and no weight loss (7).

​For you, it could be as simple as switching up the menu.

Nutrition Strategies
For High Altitude Hiking

As you probably gathered, much of why this happens to you is completely beyond your control. But, you have much more input when it comes to what you do about it.

Sometimes the name of the game is simply getting some nutrition in.. It doesn't have to be perfect. Heck, it doesn't even have to be pretty. I've known many people who aren't averse to gnawing on an unboiled block of Ramen to get energy in. Though it probably doesn't sound appealing, it works from a logistics and nutritional standpoint.

​The process of converting food into usable energy (calories) in the body happens in the small intestines. If you chew that block of Ramen well enough, the body will do its job to create the fuel source and send you on your way. Plus, there's no water to boil or cup to ask your cold fingers to articulate around a skinny pair of metal handles.

Oh, and remember those handy salt packets that come with each brick of noodles? Eat it too. Sodium is the electrolyte lost in the greatest quantity in sweat. Having a quick source to choke down may not sound wildly appetizing, but neither did medicine as a kid. And, when you're trying to climb a mountain, sometimes food becomes medicine to get you through the task at hand. 
​

Caloric Density

​In my experience, one of the most misunderstood concepts in the world of performance nutrition is that the body is either burning fat or carbohydrates; no in between. Nothing could be further from the truth. While this won't be an article on being fat-adapted or a scientific review on carbohydrates being the predominant fuel source of the active body, it is a good place to point out the body's ability to be dynamic in its utilization of fuel sources- be it fat or carbohydrate.  


The main driver of what fuel source it taps into is based on two things: 
​

1. What's available (i.e. what you've been eating or haven't been eating) and, 
   ​
   
2. How challenging the endeavour you're taking on is.

Generally speaking, the greater the challenge (i.e., the harder your breathing or "VO2 max" for the fellow nerds), the more the body is relying on carbohydrates as fuel. In fact, it's almost 100% reliant on carbohydrates as fuel when VO2 max (a measure of oxygen consumption) is at or above 85% (8).  


The trouble with this is it means the weight of your pack will be heavier than it would be should you have opted for a pack-full of fat-based foods (fat gives double the calories of carbs when compared by weight).  


So, while you can't afford to neglect carbs, you should also maximize your fat intake where possible.


One of the easiest ways to do this is by focusing on something called caloric density or finding foods that have the greatest amount of calories while taking up the smallest amount of space in your belly.  


Making sure you load up things like nuts, nut butters, butter, oils, and the like are some of the more obvious ways to ensure your needs are met. A less commonly known way to achieve this is through taking proteins that are packed in oil rather than water (think tuna, etc., for example). It takes up no more room in the gut than fish packed in water but provides far more calories for fuel.  


You can also pick up fish that naturally have more fat in them for the mountain, things like mackerel and salmon, for example.  ​

DIY Bars Made with "Special Fat"

Most bars freeze. We all know that and have likely gone to bite into a bar to only have it lead to a dentist bill for fixing a chipped tooth.


While there are some intentional steps you can take to prevent this from happening (putting the bar inside your jacket/base layers being one), some issues can't be avoided.


A tip you may try is creating your own bar out of simple ingredients like oats, dry fruit, nuts, and a fat that's largely unsaturated.  This would be almost any oil that's liquid at room temperature vs something solid (think butter or coconut oil).

​The theory behind this is that the unsaturated nature of the fat would be insurance against the bar freezing completely solid. In fact, you might need to keep the bar in the freezer until you leave to prevent it from falling apart.  ​

Powdered Mixes

As great as it is to pile calories in, calories only matter if they're from the right sources.  We talked about calorie density and how to increase it in an alpinist's diet. Like we talked about earlier, that won't accomplish delivery of the body's preferred fuel source during intense exercise- carbohydrates.

One of the best ways I've found to meet this need in a small package with clients is with a powdered drink mix like Tailwind, Gatorade, Tang, or similar. The products contain no water (read: extra weight), are easy to pack, and don't cause a mess.

​What's more is they're 100% carbohydrate and the type of carbohydrate that delivers quick energy to the muscle cells vs the delayed delivery of more complicated carbohydrates that contain large doses of fat, protein, and fiber (known to delay delivery of nutrition to you for energy).  

The other advantage of something like this is the taste.

Folks with appetite loss tend to NOT want to drink water but are open to having a flavoured beverage that veers slightly on the salty side of things.

It's tough to get calories in when nauseated, so a vehicle like this can not only be a welcome sight to many hikers but will also serve as a vehicle to get calories in where whole foods may not sound appetizing.  
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Candy You Can Suck On

There's a good dose of literature suggesting athletes experience performance improvements even if they're not eating large meals. In fact, some studies suggest a simple "swish and spit" from a carb-based drink over a placebo and dramatically improve the times of athletes in a variety of sports (9). 

Don't worry, I won't go full chemistry on you, but this tells us that something is always better than nothing, and while you may not be able to get a full meal in, you may be able to have a stash of Jolly Ranchers, Gummy Bears, or (insert candy of choice) readily available in your packs hip pouch to have on hand as a constant supply of energy during the hike.

We know that carbohydrate digestion begins in the mouth, so the simple process of sucking on candy and swallowing its juices could give you just enough energy to keep you on the mountain vs turning around and heading back down to base camp.  ​
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While we certainly cannot change factors like suppressed appetite hormones, temperature, and the feelings of overall malaise that come from being 30,000 feet above the sea, we can plan for ways to navigate around them successfully.  

Know your body and what it needs for fuel. Know what it handles...and what it doesn't. These simple nuggets can mean the difference between making a summit bid and having to turn around shy of making it to base camp. 

Citations:

1. Boyer SJ, Blume FD. Weight loss and changes in body composition at high altitude. Jour of App. Physio. 1984 Nov; 57(5): 1580-1585.
2. Honigman B, Theis MK, Koziol-McLain J, Roach R, Yip R, Houston C, et al. Acute Mountain 
Sickness in a General Tourist Population at Moderate Altitudes. Ann Intern Med. ;118:587–592.
3. P Hannon, G J Klain, D M Sudman, F J Sullivan, Nutritional aspects of high-altitude exposure in women, The American Journal of Clinical Nutrition, Volume 29, Issue 6, June 1976, Pages 604–613.
4. Amellini F, Zamboni M, Robbi R, et al. The effects of high altitude trekking on body composition and resting metabolic rate. Horm Metab Res, 1997; 29(9): 458-461.
5. Shukla V, Singh S, Vats P, et al. Ghrelin and leptin levels of sojourners and acclimatized 
lowlanders at high altitude, Nutritional Neuroscience, 8:3, 161-165.
6. Burstein R, Coward A, Askew W, et al. Energy expenditure variations in soldiers performing 
military activities under cold and hot climate conditions. Mil Med. 1996; 161(12), 750-754.
7. Kayser, B. Nutrition and high altitude exposure. Dept De Physio. 1992; 13, S129-132.
8. Williams, Melvin.  Nutrition for Health, Fitness, and Sport.  New York. McGraw-Hill. 2010.
9.  Carter JM, Jeukendrup AE, Jones DA. The effect of carbohydrate mouth rinse on 1-h cycle time trial performance. Med Sci Sports Exerc. 2004 36(12):2107-11.
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​ABOUT THE AUTHOR

Kyle Kamp is a registered dietician, and founder of Valley To Peak Nutrition.

​He specialises in helping mountain and trail athletes perform at their best on their adventures. ​

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