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What�s the best food to eat on high altitude treks, climbs or expeditions? The short answer is: whatever tastes the best and will be something you will want to eat regularly. If you�ve ever climbed above 10,000 feet, you may be somewhat familiar with the nausea, headache and general malaise associated with high altitude travel. Hopefully if you plan to spend any extended amount of time at altitude, you will have enough time to acclimatize so that you will be able to resume fairly normal eating habits. Eating to match exertion levels, and then some, is crucial in order to maintain lean muscle mass, keep sharp, and stay at a healthy body weight (or at least minimize loss so as not to be a problem when climbing). During the Himalayan Scientific and Mountaineering Expedition of 1960-1961, most subjects working at an altitude of 19,140 feet lost between 1-3 pounds per week; during the first week alone at altitude, some males can lose up to 6.6 pounds of bodyweight (Armstrong, p. 172; 188). If enough of that is insulating bodyfat, subjects may actually experience decreased tolerance to cold environments and be more susceptible to illness (NAMOHAE).
Gaining altitude at an appropriate rate is also extremely important � above 10,000 feet, it�s recommended that you gain no more than 2,000 feet a day, and �climb high, sleep low� on those days involving carries, such as on Denali. When we traveled to Kilimanjaro (19,340 feet) it took us 4 days to go from 6,000 feet to base camp at 16,200 feet, a rate that is admittedly faster than ideal, but which is fairly common for that particular mountain. On our Kilimanjaro summit day, we started the morning with hot cocoa and cookies near midnight (about all I could stomach), and didn�t stop for a bite of food (nor did we even want to) until nearly 8 hours later, when we were on our way down the other side of the mountain and running on fumes. On a climb of Mt. Rainier, people commonly go from sea level (Seattle) to 14,411 feet in 1-4 days. People opt for gummi bears, lemon drops, gu, licorice, or carb drinks on summit day, because anything else just doesn�t sound appealing. Rescue workers dropped high on the mountain and expected to jump right in to do physical labor can expect signs of mountain sickness without appropriate acclimatization; key for them is to take frequent rest breaks and pressure breathe immediately.
The key to success at altitude is to hydrate regularly, above all else. Dehydration exacerbates symptoms of altitude sickness and diminishes appetite further, so if you feel the start of a headache, try warding it off with a carb-loaded beverage (shoot for 3-4 liters a day, containing 100-250g carbs in addition to your food calories; Askew, p. 1). While water is usually the beverage of choice, I find I need the regular, ongoing dose of carbs to help keep me going. Experiment to find what works for you. The other key is to eat plenty of food (or suck on hard candies or gu), as much as your body will tolerate. In fact, you�ll notice in the recommendations below that cider, juice mixes, cocoa, tea, lemonade, Gatorade, soups, and the like all involve plenty of water and carbs; the more per meal, the better.
Macronutrient ratio and calories
What about the mixture of carbs to protein to fat? Carbohydrates are certainly important for any endurance activities such as marathons, triathlons, and backpacking. Do they behave the same at altitude, and in the cold? According to Armstrong�s research, most mountain climbers prefer the taste of a high-carbohydrate, low-fat diet at altitude, and many find fatty foods to be unpleasant or distasteful. Carbs are helpful in replacing depleted muscle glycogen stores, preventing protein from being catabolized or burned as energy, and they require less oxygen for metabolism. According to Askew, �Fat, while tolerated relatively well in the cold at sea level, may not be as well tolerated in diets at high altitude� Although high-fat foods are energy dense and reduce the weight/calorie aspect of food carried on climbs, fat requires more oxygen for metabolism than carbohydrate and will place a small, but added burden upon the already overtaxed oxygen economy of the climber.� (Askew, p. 3) Climbers who reach for high fat foods usually are not going to be consuming as many carbs, which can result in low blood sugar that, in turn, can lead to confusion, lack of simple coordination, and disorientation.
Some people end up craving fats and dig into peanut butter (that hasn�t frozen!) or add butter to whatever they can. In terms of the best recommendations for ongoing treks and sustained energy, Carolyn Gunn, the author of the Expedition Cookbook (Hanson, p. 17), suggests planning for 4,000 calories per person per day for a trip such as Denali, in the ratio of 60-65% carbs, 20-25% fat and 10-15% protein (what amounts to about 2 pounds of food per person, per day, not counting packaging.) Expenditure can be as high as 6000 calories/day, depending on altitude, extreme temperatures, and performance requirements for any given day (NAMOHAE). The raw energy requirements increase 15-50% over that needed at sea-level for comparable exertion, and will obviously depend on the size and gender of the individual; a 115 pound woman, for example, won�t need as much food as a 175 pound man, assuming they�re doing comparable work. At the same time, food intakes typically fall 10-50% during altitude exposure, depending on the rapidity of ascent and the individual�s susceptibility to altitude illness such as AMS (acute mountain sickness). (Askew, p. 1)
Interestingly enough, one summary reported: �Women may have a biological advantage at altitude. In general, they suffer less severe symptoms of AMS and do not experience as great a depression in appetite and food intake as do their male counterparts� (NAMOHAE). Women may be challenged by other issues at altitude (such as toting comparable loads at a lower bodyweight) but being at altitude per se doesn�t seem to be one!
What works for you�
In my own experience on Kilimanjaro and Rainier, cheddar mashed potatoes with freeze-dried turkey added to it seems to be the one freeze-dried meal that stays down nicely and fuels me for summit day; chicken noodle soups, hot cocoa, packets of gu, and carbohydrate-containing drinks definitely �feel� better in my mouth and stomach, and go down much more easily than jerky, nuts, or the tastiest candy bars, which simply take too much energy to chew, swallow, absorb into the bloodstream, and then digest. The more quickly a carbohydrate is absorbed into the bloodstream (i.e. in the form of fluids) the faster it can be used as energy. Each individual needs to find out what works best for his or her body and stick with it.
To determine what might work best for you, test out a variety of foods at elevations above 10,000 feet and scrap what doesn�t appeal there, as it probably won�t get any more palatable higher up. Take the tastiest foods you can find, and plenty of different options, as you�ll likely only get increasingly finicky higher up. Try to ward off monotony; I can�t imagine anything worse than having the same food 4-5 days in a row if you didn�t like it the first time you tried it. Try cooking or preparing the food as you will have to do in the field, and test out no-cook food when it�s frozen to see if it�s still edible. My husband once cut a gash in his cheek when he tried to bite into a too-cold Powerbar and swore he�d never buy one again! Test out additives to see if your system can run well on curry or other spices; you may find that the chicken gumbo that was fine at base camp on Mt. Baker just doesn�t appeal to you in the least at high camp on Denali. Some recommendations from Hanson and Hanson (who have been to Denali 3-4 times) include:
Final fragments: frequent food foibles
So what do you tell someone who tells you to eat string cheese to plug you up? Constipation is actually a quite common complaint at altitude, where decreased oxygen slows down the function of the intestines and excessive fluid losses rob water from the colon (NAMOHAE p. 3) The opposite can also occur due to food preparation with less-than-adequate hygiene; diarrhea is quite common among climbers in Africa, and several ways to prevent suffering from diarrhea are 1) clean hands thoroughly before eating; 2) do not eat any exterior surfaces of tomatoes or fruit; 3) avoid any vegetables that haven�t been boiled; and 4) after day 2 of a trek, avoid eating meat of any kind that has not been freshly killed or somehow refrigerated, unless it�s been dried and preserved (such as jerky sticks.) And lastly, if you suffer from intestinal gas, limit the amount of dehydrated food high in carbohydrates that you eat, as they tend to cause gas production. Happy eating up high!
Armstrong, Lawrence E., PhD. Performing in Extreme Environments. Human Kinetics: Champaign, 2000. pp. 165-195.
Askew, E. Wayne, PhD. �Nutrition at High Altitude� at www.wms.org/education/Nutrition%20at%20Altitude..htm
Hanson, Kurt and Marcia; Seminar: Planning An Expedition to Denali; Seattle Mountaineers, Feb. 2002.
Kundrat, Susan, MS, RD, LD: �High Altitude Nutrition� at www.nutrifit.org/nutr_info/altitude.html
�Nutritional Advice for Military Operations in a High-Altitude Environment� (NAMOHAE) at www.usariem.army.mil/nutri/nuadalti.htm