Intensity, duration, the demand of the terrain, pack weight, fitness level, altitude, and habitual food intake largely determine how much fuel for exercise is derived from carbohydrates, fat, and protein. All three are used as sources of energy at any given time, but intensity and duration of exercise are the primary factors that determine the extent to which one is used over another. The higher the exercise intensity, the more carbohydrates contribute to fueling needs. At low to moderate intensities, like very easy running, walking, hiking, and backpacking, fat is typically the dominant fuel source.
Backpackers and ultra-endurance hikers, walkers, and even some runners generally spend more time a lower percentage of their VO2max and in lower training zones. For example, Zone 2 with some time in Zone 3 and bursts into Zone 4. Nutritionally speaking, we can therefore fuel with both fats and carbohydrates as well as some protein for these activities.
Fats are more calorically dense than carbohydrates, meaning that they provide more energy per gram. Therefore, foods higher in fat can help lighten pack loads while also supporting your very high caloric needs on the trail. One study conducted on three backpackers reported a daily caloric expenditure of ~3000 – 5000 calories where gross energy expenditure ranged from 3.1 to 16.8 calories per minute of activity. Similar (and higher) daily energy expenditure in ultra-endurance walkers and runners has been observed.
Limited food supplies combined with large energy expenditures can lead to a massive energy deficit that can cause losses in tissue mass as well as suboptimal performance.
In competitive ultra-endurance athletes, the magnitude of the energy deficit has been observed to be correlated with performance. The larger the deficit, the worse the performance outcome. Therefore, narrowing the gap between energy intake and expenditure is imperative for competitive ultra-endurance athletes, and fats can play a key role in this.
Typically, recommendations suggest 25-30% of total daily calories come from dietary fats. However, you might require far more than that to meet your trail caloric needs and to achieve a reasonable pack weight.
Relying solely on fats for fuel needs will limit the intensity of exercise that can be performed and restricts one’s capacity to do anaerobic work. Carbohydrates are very beneficial when ascending steep inclines and surging over hills, for example, or when working at higher speeds.
Carbohydrate recommendations for endurance athletes:
Intra-workout carbohydrate recommendations are 30-60g/hr for endurance events 1-2.5hrs and 70-120g/hr for ultra-endurance events >2.5hrs. The higher amounts of carbohydrates will require the athlete to train their gut to tolerate that amount.
However, carrying that amount of carbohydrates over very long distances will add weight to a pack and take up valuable storage space as well. And as previously discussed, backpackers and ultra-endurance walkers, hikers, and some runners aren’t utilizing just carbohydrates as their fuel source during exercise.
Rather than aiming for only a carbohydrate goal, we could instead aim for a calorie amount per hour that consists of protein, carbohydrates, and fats: ~240-480 calories/hr.
Timing higher carbohydrate consumption around challenging terrain (e.g., strenuous uphill portions) or in sections where you want to move at higher speeds would be advantageous.
Protein can contribute to up to 10% of total energy used during endurance exercise. The amount is influenced by intensity, duration, and the level of glycogen/glucose availability in the body. Less available glycogen/glucose = more protein used as a fuel source, which can lead to muscle loss.
Protein recommendations for athletes are > 1.6g/KG BW/day to enhance recovery and preserve muscle mass. However, carrying this amount of protein, especially for those on the trail for >1 week in a pack, often proves difficult to achieve. Aiming for no less than 1.2-1.6g/KG BW/day is likely more realistic for many.
Suggestion: look for energy bars that also contain ~5-10g of protein! For example, the peanut butter chocolate chip GoMacro bar contains ~11g of fat, 39g of carbs, and 11g of protein.
Endurance recommendations for hydration:
Consider performing a sweat test before leaving on your trip to determine how much fluid you lose per hour of activity. Do your best to mimic the conditions you’ll be in. Here’s how you can perform a sweat test:
Input your metrics into the following equation to determine your hourly sweat rate:
((Change in weight x 16oz = pre-workout fluid) + oz of fluid consumed during exercise) / time exercised (hr)
Example:
Keep in mind that this sweat rate only applies to the activity you performed at the intensity you performed it at in the conditions you exercised in.
You can also have your sweat tested to determine your electrolyte replenishment needs. Levelen is one company that conducts sweat content testing.
Other recommendations:
Products and foods that contain mixed macronutrient sources will help minimize the gap between calories expended and calories required, support fueling needs, provide protein sources, and reduce pack weight.
Breakfast can be a balanced mixture of protein, dietary fat, and carbs to help energize you and get you started out on the trail. For example, Backpacker’s Pantry granola with almonds, blueberries and milk or Next Mile Meals sausage scramble with a large side of oatmeal.
Lunch can either be more snack-based or can be a complete meal. One of my personal favorites out on the trail was tortillas, cheese, and salami.
Aim for a higher protein meal with sufficient dietary carbohydrates and fats in your last meal of the day to help support muscle recovery and replenish depleted fuel stores. A for a 3:1 carb to protein ratio (e.g., 20g of protein and 60g of carbohydrates) is ideal with sufficient dietary fats to provide more calories. Bushka’s Kitchen hunter’s pie with ground venison packs 33g of protein, 76g of carbohydrates, and 40g of fat.
Snack frequently between main meals!
