Long-Distance Backpacking Nutrition According to Science

Sometimes the hardest part of a trek begins before you even set foot on the trail. Figuring out your nutrient needs and how they change over time can often be a complicated and daunting task. We’re here to help. We’ve compiled research and actual practical experience to help break down the process of calculating nutrient needs (and what exactly that means) because the hardest part of a backpack trip shouldn't be what you eat.

First, let’s break down what your body is doing to get the fuel for an activity like backpacking:

The nutrients that you consume (think fats, proteins, and carbohydrates) are broken down to form ATP (adenosine triphosphate). ATP provides energy to power your body whether you are sitting or during activity. 

Photo by Seth Anderson Photography

After the start of exercise, ATP and creatine phosphate provide the initial burst of energy, then a mixture of systems with and without oxygen take place to help sustain activity. For endurance activities, the aerobic (with oxygen) system is sustaining energy because the lungs have had the time to catch up with the body to provide the oxygen needed for this system to take place. At low intensity exercises and rest, the primary fuel for the body is from fats; for high intensity exercises, carbohydrates are the primary fuel. The key term here is primary— glucose, fatty acids, and amino acids all play a role in this aerobic metabolism. 

Now, what exactly does this mean in terms of nutrients to pack? Your carbohydrate needs will increase with increased activity to maintain muscle glycogen stores (this is what helps you keep going without bonking-  thank you carbs!). However, it is important to consume a balance of macronutrients including having enough fat and protein to help with aerobic metabolism. RecPak has a balanced macronutrient makeup designed with this in mind while still staying at an ultra-light weight. Your caloric needs will also increase as your activity increases, especially with more difficult terrain and increased pack weight. 

How to Determine Personal Nutrient Needs

Using your body’s basal metabolic rate (BMR) and activity coefficient for endurance backpacking is a good way to get an estimate of your caloric needs during a trip. BMR is the number of calories your body would burn if you were to lay in bed and sleep all day and night (if only!). This number is simply what your body needs to maintain basic functions and is impacted by many factors including age, muscle mass, body size, genetics, and more. This truly is an estimate of caloric needs on the trail, and it is important to remember your needs will increase through the duration of the trip. Use this as a guideline, and adjust to meet your own personal preferences. Kansas State University has a great reference for this method— here’s what you do:

• To calculate your BMR,  we will be using the Harris-Benedict equation (listed in table 1.1). 

• Then, multiply your BMR by an activity coefficient to get a rough estimate of caloric needs. These activity coefficients are shown in table 1.2.

• Now you have estimated calorie needs for your trip! 

Still confused? Here’s an example: 

Person: Female, height of 5’6” (66 inches), weight of 160 pounds, 23 years old

1. Calculate BMR: BMR=655+(4.35*160)+(4.7*66)-(4.7*23)=1553.1 calories BMR (this is how many calories this person would burn if they were to be in bed sleeping all day and night)

2. Multiply by activity coefficient for very active individual (1.725): 1553.1*1.725= 2679.098 calories (this is an estimated amount of calories you body will need with a high level of exercise)

Getting enough nutrients and figuring out what to pack for a trip is a problem that Joy Seward, an NOLS instructor and co-founder of RecPak, knows all too well. Often, one-to-two week long expeditions take her over 100 miles through a variety of different technical terrain. As an instructor, Joy is expected to not only care for herself but is also responsible for the safety of her students. She has to manage her nutrition intake inorder for her to have the energy and alertness that is required for her job. 

Joy noted, “Food really does matter, and it equals longevity. The reason why I am able to do long format expeditions is because of having high quality nutrition with me.” We know that nutrition and how we fuel impacts how our bodies perform in the field, but Joy noted how it can have a large impact on our mental fortitude as well — “I was just leading an outdoor course and the days are really long days in the backcountry terrain  where you need to be sharp, you need to be with it. I have always felt that if you are not able to keep your glucose levels up it can be really stressful when it’s time to make hard decisions, especially in the afternoon…. Being able to have the mental fortitude to have high standards around safety and being able to have the energy and capacity to push yourself…is what makes a safe environment.” Without having the fuel to make these crucial game-time decisions, Joy could have chosen an option that put both herself and her crew at risk. 

Nutrition in the backcountry can often be a confusing topic, but can be the difference in being able to push to a safer campsite or pedal those last few miles. Use the equation and information provided to help you go those extra miles, keep yourself and your crew safe (thank you Joy for the insight), and help you better plan your next backcountry adventure.  Proper nutrition can pretty much take you anywhere, but ultimately you still have to make the decision, where is it going to take you?