If you’re asking yourself this question, perhaps you’ve read stories or watched movies about hiking or mountain climbing that depict these activities as a rigorous pursuit in the temptation of fate. The kind of stories where the subjects stagger away from their respective undertakings an unrecognizable shell of their former selves.
Alternatively, you might be wondering if a Kilimanjaro summit attempt is going to help get you into those jeans you’ve been hiding in the back of your closet. Whatever the driving force behind that curiosity, in order to arrive at an accurate answer to this question one must first gain an understanding of several key variables and how those could manifest at high altitude.
Before we delve into the physiological aspects of high-altitude hiking on a more general level, it is worth prefacing with some pertinent information about climbing Kilimanjaro.
Kilimanjaro is a truly unique experience in that you can walk to the 19,341’ summit without any technical climbing. You also won’t be carrying a heavy pack. Your team of Peak Planet porters will handle the lion’s share of the gear by transporting it from camp to camp. Climbers are only expected to carry a small daypack containing the day’s water, snacks, and appropriate clothing layers for the anticipated conditions.
In addition, routes up the mountain take between eight and eleven days from start to finish, meaning the trip length is limited by the route. Also worth noting is the extremely slow and steady pace set by your guides for the duration of the ascent, meant to both maximize the time spent acclimating to high altitude and to minimize the impacts of fatigue.
And finally, you eat like royalty during the entire trip. You get three hot meals a day, as well as many snacks and drink options.
So if this is the case, then why do people lose weight on Mount Kilimanjaro trips?
You Will Burn More Calories.
Hiking is an inherently strenuous activity. Depending on factors such as body weight, pack weight and degree of incline, one might burn between 300-600 calories an hour. In addition, acclimatization to high altitude leads to a slight increase in basal metabolic rate, which is the amount of energy needed to keep your body functioning. More on that later.
Considering that the typical daily hike can take four to seven hours and the brutal summit day can take between 11 and 15 hours, the math here begins to add up quickly. It is conceivable to burn somewhere in the range of 3,000 to 5,000 calories on a normal day and a whopping 5,000 to 7,000 calories or more on summit day.
Though energy expenditure on Kilimanjaro is variable from person to person, a shared set of factors determine where one might fall on that spectrum. There have been studies that have examined weight loss at high altitude which have found that people do burn more calories. However, exercise at high altitudes cannot fully explain why weight loss occurs.
You Will Want to Eat Less.
With weight loss predicated on whether calories consumed offset the number of calories burned, it’s important to note that Peak Planet climbers are fed extremely well. Each of the three daily meals are thoughtfully prepared, easily digestible and calorie-dense. And you are encouraged to eat, even if you don’t feel like it.
Porridge, eggs, sausage, toast with jam, and fruit are some examples of the types of breakfast foods offered, while beverages throughout the day include coffee, hot chocolate, juice, and tea. Lunches include clear soups, sandwiches with meat and cheese, pasta, and treats like cookies or cake, while dinners may include items such as creamy soups, bread, vegetables, chicken, beef, fish, pasta, rice, and dessert.
When arriving at camp each day, climbers are greeted with snacks like popcorn, peanuts, French fries, and cookies to help boost morale and provide quick, easily digestible carbohydrates and protein. While you may also bring with you your own snacks for the trails, it’s by no means essential.
While the list above may inspire you to run to check your pantry, less inspiring are the symptoms of altitude sickness (to be continued), one of which includes decreased appetite. Studies have found that lack of appetite is one of the more significant causes of weight loss at high altitude. In fact, weight loss can occur at high altitudes in the absence of exercise.
One study reported that the participants at high altitude who had unlimited access to food consumed nearly 730 calories less than they typically did at a normal altitude. The decrease in appetite is caused by elevated levels of leptin, the protein hormone that plays a role in appetite control and metabolism.
You Will Dehydrate Faster.
Continued water consumption is easy to overlook when outside temperatures approach freezing and your focus tends to drift more toward doing things to keep warm. Fluids deplete no matter the air temperature, and more so at high altitudes where humidity is considerably less, so the importance of fluid intake cannot be overstated.
The daily recommendation for water consumption absent strenuous activity is two liters. For moderate activity in moderate temperatures, one should drink no less than a half liter per hour, and the volume recommendations go up from there depending on the activity, air temperature, and sweat rate. At high altitudes, however, the game changes entirely, and water requirements substantially increase in order to facilitate the body’s natural responses to decreased oxygen concentration.
Normal bodily processes, such as breathing rate, accelerate at high altitudes to compensate for the lack of inspired oxygen per breath. The byproduct of these accelerated processes is increased urine production to rid the body of cellular waste and an increased need for water to carry them out.
Furthermore, to combat symptoms of altitude sickness, many climbers take Diamox (acetazolamide) during the climb. The diuretic properties of this drug aim to prevent fluid accumulation in the brain and lungs – the most likely killers at high altitude. This amounts to even greater frequency of urination and water loss, making the need for fluid intake a virtual constant. Given the fact that the body is comprised of 60% water, several days of accumulated fluid debt can equate to measurable weight loss.
Your Metabolism Increases.
Studies have also concluded that acute high-altitude exposure increases the basal metabolic rate. Basal metabolic rate is the number of calories your body needs to accomplish its most basic (basal) life-sustaining functions. In other words, you burn more calories just by being at high altitude.
Researchers determined that there is a 6%-28% increase in overall BMR at high altitudes. As you acclimate to the altitude, the BMR lowers, but does not return completely to baseline.
Weight Loss is Not a Good Thing.
Though some people might look forward to shedding a few pounds during their Kilimanjaro expedition, we certainly do not want climbers to actively attempt to lose weight.
The above factors which cause weight loss also make your climb more difficult. The culmination of each of these variables when combined with the rigors of ascending and descending more than 25,000 combined feet of elevation can make an already challenging endeavor worse. Armed with this information, when the urge to consume fewer calories and drink less water comes, make the effort to continue eating and drinking as much as possible. Doing so in spite of environmental and physiological conditions will be best practice, and will serve to reduce severity of the effects of acute mountain sickness, increase stamina and recovery, minimize weight loss, and increase the odds of a successful summit attempt.