Disclaimer: The following information gets kind of technical. While I have no formal education in nutrition, this subject is of great interest to me as someone who relies on a healthy and strong body to do the things that I love. Most of the information I regurgitate below was gleaned in a reading of “Training for the New Alpinism” by House and Johnston, an excellent book that functions as a manual for climbers looking to get super fit for super climbs. It just so happens that mountaineers share many of the same fitness and nutritional goals as thru-hikers, mainly incredible endurance and the ability to keep the body fueled for adventure. Heed my advice, read the book yourself, or ignore all of it, but beware that my writing is second hand information that is potentially ill-remembered. I tried hard to get things right, and even reread parts of the book, but I’m still just a dude writing this at home in his underwear. Take it all with a grain of salt. Wait, you’ll need a lot more than that to replace what you sweat out on the trail. Have a spoonful, on me.
Trail “nutrition” does not exist. This post should really be called “Calories” because that is what it’s about. Figuring out how to eat enough calories to keep moving forward without wasting away is the primary food-related struggle encountered on a thru-hike. Unfortunately, this means leaving your salads and fresh fruit behind. Fortunately, this means that you can eat as much junk food as you want. Trail food is fuel to propel the hiker to the next town and needs to be as light as possible, easy to prepare, and capable of taking a beating. “Nutrition” should be reserved for towns where each stop is an opportunity to cram healthful foods to make up for the lack of wholesome choices on the trail. I hear that scurvy isn’t that fun, so eat what you want on the trail, but make good decisions in town. Besides, burritos cover most, if not all, of the food groups. Do yourself a favor, eat a burrito.
Common belief holds that hiker hunger hits after 10 days on the trail. Hiker hunger is both a gift and a curse. While it allows you to down a pint of ice cream in one sitting guilt free or smuggle an 18” burrito into your gastrointestinal system, it is a harsh master, an ever burning furnace that demands more, more, MORE! In towns, where access to an endless supply of food items that have haunted your dreams is no longer an issue, wanting to eat EVERYTHING is a great feeling. On the trail, where one must carry each calorie that one consumes, planning a menu is mostly an anxious exercise in simple arithmetic, balancing calories with ounces so that you have enough energy to push through the next section without breaking your back trying, and ruminating on the answers to important questions. “Can I really eat mashed potatoes 4 days in a row?” Yes, yes you can. Yes you will. Another hiker described the results of a resupply as what you would end up with if you let an 11 year-old loose in a grocery store with zero budgetary constraints. A lot of snacks, candy, and no fresh food. Just a pile of junk food, or rather, hiking food. It just so happens that the food that you’re not supposed to eat in normal life is perfect when you start considering terms like “calorie dense” and “non perishable” desirable characteristics.
I think we can all agree that sweeping generalizations have their flaws, but I’ll take a shot at one anyway. As I mentioned above, number of calories, not their source, are the most important part of any resupply, provided that some thought is given to replenishing bodily stores of essential vitamins and nutrients when they are readily accessible in towns. A helpful rule of thumb to consider is the 100 calorie per ounce threshold. Carrying a packful of food with this average calorie density should be a manageable task, adequately restoring the energy used on a daily basis without being too bulky or heavy. At this rate, 4,000-5,000 calories (a reasonable daily intake requirement) will weigh roughly 3 pounds. That’s 3lbs, per day, on your back. If that sounds like a lot… it is, which further illustrates why being conscious of calorie density is as important as anything else on a thru-hike. Here are some examples of the calorie density (cal/oz) of some typical trail foods:
- Olive oil: 252
- Peanut butter: 168
- Oreos: 140
- Snickers: 138
- Granola: 110
- Mashed potatoes: 110
- Salami: 110
- Pop Tarts: 108
- Flavored oatmeal: 105
- Clif Bar: 104
- Tortillas: 80
- Beef jerky: 80
- Tuna: 30
Hopefully this clarifies the calorie game a little bit. Of course, protein is an important part of daily needs, but a calorie of protein rich foods such as tuna or jerky cost a lot more in weight than food items that predominantly provide calories from fat. For example, 1 gram (whoa, unit change. Watch out!) of protein provides 4 calories while 1 gram of fat provides 9 calories. That’s over twice the energy density! Ounces of low calorie foods, while essential, must be balanced with ounces that are calorie-rich. Are you bored yet? Okay, but allow me one more point regarding macronutrients.
While carbohydrates have an equal calorie density (4cal/gram) as protein, carbs should account for a disproportionately large percentage of total calorie intake. This discrepancy is due to how the body metabolizes energy. Carbohydrates (sugars) are easily processed and stored as glycogen, which is instant energy on tap for a burst of exertion such as sprinting up a hill. The body has roughly 2,000 calories of energy stored in this form, ready to go. But 2,000 calories only gets you so far, and certainly not the 20+ daily miles hikers tread, which is where the value of fat is truly realized. Even though it burns more slowly, the body contains 100,000 calories worth of fat, ready to fuel well trained individuals during feats of incredible endurance. That will get a hiker very far indeed. The key is training your body to tap into this vast energy source, which is no small feat and takes time. Lastly, protein is the energy of last resort, rarely used until carbs and fats have been depleted. Protein makes up the very muscles that keep a person moving, so it makes little sense to cash it in for energy unless the other tanks are empty. Protein is needed to maintain and build muscle, but it is not an energy source.
Just to make things more complicated, a hiker’s nutritional/calorie requirements can vary widely with terrain, mileage, elevation, temperature, point in the hike, etc. In the early going, weird and incredible physiological changes help adapt the body to increased physical demands; expanding the capillary bed, strengthening tendons, and building muscle. Later, maintenance and recovery take precedence as the miles and stress accumulate. Patchwork versus sculpting, each with unique nutritional dependencies. During the more challenging portions of the trail in the Sierra and the frigid temperatures in Washington, I estimate that my calorie requirements increased by up to 30% relative to easy cruising through Oregon flatlands. It takes extra energy to climb hills, stay warm, and produce the additional red blood cells needed for acclimatization. Being unprepared for this energy discrepancy isn’t likely to destroy a hike, but it is the difference between going to sleep full or hungry. Also, it is important not to overlook daily mileage as the primary factor dictating daily calorie needs. I believe there is a tendency to focus on “days of food” rather than “miles of food”, a crime of which I am most certainly guilty. Clearly, it takes more calories to hike 30 miles in a day than 20 miles, all else being equal. As the body adapts, allowing more miles hiked in each day, the daily calorie intake should increase with it, meaning that the menu will change over the course of a hike. This seems obvious to me now, but I commonly budgeted each resupply in terms of “days”, regardless of how many miles I planned to hike each day. Though this rarely makes an impact as mileage increases gradually and is generally consistent day to day, allowing for gradual menu tweaks to match, the calorie comparison between day 10 to day 100 can be quite dramatic.
So how should this information be used? Calorie density is an important metric to keep in mind and should impact food choices. Peanut butter was my calorie trump card, stepping in with its stellar cal/oz anytime I was deficient. I always carried a whole jar (or Nutella) no matter how short the section. The other information has less practical value, but is nonetheless beneficial if remembered in context of a body’s needs over the course of a thru-hike. Listen to cravings, they tell you what your body needs. Thru-hiking is unlike all other backpacking trips or sporting ventures, in that running a calorie deficit is unsustainable and will doom any attempt to failure. The distance is too far and the days too numerous. The brain wants to go the distance and the body will take it there if it is given the fuel for which it asks. Don’t be stingy. Eat a burrito. And finish.