GORP
Average read time 7 min

When I started hiking, I quickly learned that summer foods and winter foods are not created equal. Also, the strategies for eating on winter day hikes are different. We say the lunch begins and ends at the trailhead. In other words, there is no formal “break” for lunch; you eat as you go.

This post will address types of foods for winter hiking, calories and nutrients, and hydration (even though that’s covered here).

Table Of Contents

Calories and nutrient mix

There seems to be a relationship between increased energy intake and cold environments. The proposed mechanisms range from the hobbling effects of winter (Institute of Medicine, Committee on Military Nutrition Research & Marriott, 1996), the need to maintain body core temperature via increased energy production (Westerterp-Plantenga, 1999), and hormonal influences such as increases in ghrelin and decreases in leptin, both involved with hunger (Charlot et al., 2017).

We know that a winter hiker must eat enough to prevent blood glucose depletion, premature fatigue, and subsequently hiker’s hypothermia (Young & Castellani, 2007; Tipton et al., 2006). Hiking in winter is no time to put your body into a caloric deficit. Maintaining adequate calorie intake is essential to balance energy output and intake to create an “energy equilibrium.” A lot goes into how many calories you burn when hiking—for example, walking speed, bodyweight, pack weight, grade, trail conditions, and environment.

How many calories burned hiking?

Using the modified Load Carriage Decision Aid, a person who weighs 150 LBS and carries a pack that weighs 25 LBS has a total weight of 200 LBS. Traveling at 1.5 MPH on a grade of 15%, the hiker would be expending 508 Kcal/hour or 339 Kcal/mile. Since we do not hike continuously on an incline, our total energy expenditure would vary on the trail’s level and downhill segments. One of the main problems with this equation is that it does not consider terrain conditions (e.g., evenness, snow, ice, sand, rocks, etc.). But we’ll call it close enough!

We can see that hiking with a heavy pack expends many calories, and we need to eat frequently and sufficiently to maintain energy balance on the trail. Studies have repeatedly demonstrated that one of the critical factors in preserving energy intake in cold environments is having palatable foods available to eat (Westerterp-Plantenga, 1999). 

Diet composition in the cold, lessons from the military

In studies of military personnel and self-selected macronutrients in cold environments, there was a similarity of food composition (Institute of Medicine, Committee on Military Nutrition Research & Marriott, 1996). Generally, the breakdown was about 13% protein, 42% fat, and the remainder from carbohydrates across studies. In other words, the combination of fats, protein, and carbs did not differ much between studies. However, the foods should also meet the physiological demands of the activity.

Thus, the focus of food choices should be tastiness, high calories, and nutrient-denseness for the activity.

Types of nutrients

I have seen the recommendation of packing high protein-high fat foods for winter hiking with no mention of carbohydrates; this would be detrimental to endurance performance. Protein and fats are high in calories, taste good, a definite plus but are slow to digest. Protein and fat increase heat production due to complex digestive processes, which may be unproductive during endurance exercise (McArdle et al., 2013). Due to peripheral vasoconstriction and a reduced blood flow to adipose tissue, fat utilization may be blunted in cold environments (Porcari et al., 2015). To an extent, all three nutrients are used in some percentage during endurance exercise, depending on intensity and duration. In all practicality, carbohydrates and fat are the body’s primary energy source during endurance activities (McArdle et al., 2013). 

Carbs

Carbohydrate is a vital energy source during aerobic and anaerobic exercise. A 24-hour fast or low carbohydrate-normal calorie diet can nearly deplete resting glycogen reserves (McArdle, Katch, & Katch, 2015). Conversely, a two or three-day carbohydrate-rich diet can increase glycogen store two times than a moderate carbohydrate diet (McArdle, Katch, & Katch, 2015). Any significant reduction in the body’s carbohydrate supply during exercise will result in fatigue and decreased performance. 

As exercise progresses toward high-intensity aerobic activity, carbohydrates’ contribution approaches 70% of total energy metabolism (McArdle, Katch, & Katch, 2015). The selective dependence on carbohydrates serves two purposes: (1) it is two times faster than fat or protein metabolism, (2) it generates 6% more energy per unit of oxygen consumed (McArdle, Katch, & Katch, 2015). 

As glycogen depletes and activity duration increases, fat oxidation is providing an increasing amount of energy. With this, exercise intensity begins to fall. As intense aerobic exercise reaches 90 minutes, it is not improbable that uncompensated blood glucose levels can approach hypoglycemic levels (McArdle, Katch, & Katch, 2015). This hypoglycemia is associated with symptoms including irregular heart rhythm, fatigue, pallor, shakiness, anxiety, excessive sweating, confusion, and blurred vision (Fisk, 2017), and an increase in sports-related injury (McArdle, Katch, & Katch, 2015).

The challenge of maintaining carbohydrate feeding during exercise is key to avoiding fatigue, hypoglycemia, and injury.

Fats

Conventionally three patterns of fat utilization are identified with exercise. First is the metabolic cross-over effect in which the fat oxidation at rest is “crossed over to greater carbohydrate utilization as exercise intensity increases (Campbell & Spano, eds., 2011). The second consideration is the duration effect, which involves increased fat utilization with lower intensity, long-duration activities (Campbell & Spano, eds., 2011). Finally, fat utilization will also increase as glycogen stores deplete (Campbell & Spano, eds., 2011). As carbohydrates act as a carbon primer for fat entry into the Citric Acid Cycle (Campbell & Spano, eds., 2011), limiting carbohydrate limits fat metabolism. Remember this: fat burns in a flame of carbohydrates.

Proteins

Protein may contribute up to 5-10% of prolonged aerobic exercise depending on intensity and duration (Campbell & Spano, eds., 2011; McArdle, Katch, & Katch, 2013).

Food & fluids in winter conditions

The nature of winter hiking lends itself to freezing. Although you may be adequately dressed and warm as you exert yourself, the items in your pack do not enjoy the same fate—liquids in Nalgene bottles and foods in your pack can freeze. 

One of the first things the winter hiker must do is prepare and pack foods to address freezing. For example, a hiker may enjoy cheese on the trail. In the winter, cheese may freeze in an uninsulated pack. This “packing problem” may make cutting cheese impossible; the solution may include buying cheese that is cubed. The hiker then can store the cubed cheese in a warming pocket before eating to soften.

Likewise, any liquids stored in a non-thermal container will freeze from the top down. Some have suggested keeping a Nalgene bottle upsidedown will prevent the cap from freezing shut and keeping the drinkable liquid at the opening. Try storing your bottle on the inside of your pack instead of one of the outer pockets. This may help retard freezing. Many hikers bring warm drinks into the backcountry in the winter. Drinks such as hot chocolate may be a solid choice as the beverage provides carbohydrates, fat, and protein.

Showing hiker with water bottle on outside pocket of backpack.
Photo by Maël BALLAND from Pexels Avoid packing bottles on the outside of your packing during Winter

Leave the energy bars at the gym in the winter; they become like a brick in the backcountry. Bring brownies or cookies that you prepare by chopping up or crackers like Ritz. Dried fruits with chocolate and nuts (GORP), be creative, and make your own GORP (or try one of these). We dice cheese or meats. Some candies work well. Remember, the food you bring should be tasty!

Fluid balance is critical during exercise. Cold environments may blunt your thirst drive. Additionally, cold weather stress induces cold-diuresis, which may increase fluid loss. Bring drinks you enjoy. Most likely cold water is not going to satisfy you on a 10-degree day. Teas or another favorite hot drink may do the trick.

But alcohol makes me warm! Nope.

It may sound silly that I have to say this, but NO alcohol. Yes, I’ve seen it in the backcountry. Alcohol may give you a “warm” feeling, but it does not warm your body. This feeling of warmth is due to peripheral vasodilation moving blood to the extremities. This shift in blood volume can lower body core temperature, which may be hard to perceive.

Sports drink?

During the hike, we have a sports drink on hand. The ingestion of a 6-8% carbohydrate solution drinking 8-16 oz every fifteen to thirty minutes using a combination of glucose, sucrose, maltodextrin, or small amounts of fructose is beneficial at maintaining blood glucose (Campbell & Spano, 2011). The inclusion of branch chain amino acids in the solution may help. Carbohydrate to protein ratio of 4:1 has been shown to improve endurance (acute and subsequent) and reduce muscle damage (Campbell & Spano, 2011). There are many on the market. We use Accelerade, which contains a 4:1 carbohydrate/protein ratio. The product comes in different flavors for greater palatability.

References

Charlot, K., Faure, C., & Antoine-Jonville, S. (2017, 6 10). Influence of Hot and Cold Environments on the Regulation of Energy Balance Following a Single Exercise Session: A Mini-Review. Nutrients, 9(6), 592. doi.org/10.3390/nu9060592

Fisk, M. (2017, October 03). Exercise-induced non-diabetic hypoglycemia. Retrieved from
https://www.livestrong.com/article/326019-exercise-induced-non-diabetic-hypoglycemia/

Institute of Medicine, Committee on Military Nutrition Research & Marriott, B. M. (1996). Nutritional Needs in Cold and High-Altitude Environments: Applications for Military Personnel in Field Operations (S. J. Carlson, Ed.). National Academies Press.

McArdle, W. D., Katch, F. I., & Katch, V. L. (2013). Sports and Exercise Nutrition (4th ed.). Lippincott Williams & Wilkins.

McArdle, W. D., Katch, F. I., & Katch, V. L. (2015). Exercise Physiology Nutrition, Energy, and Human Performance. (8th ed.). Wolters Kluwer Health.

Porcari, J. P., Bryant, C. X., & Comana, F. (2015). Exercise Physiology. F.A. Davis Company.

Spano, M. A. (2011). NSCA’s Guide to Sport and Exercise Nutrition (B. I. Campbell, Ed.). Human Kinetics.

Westerterp-Plantenga, M. S. (1999, November). Effects of extreme environments on food intake in human subjects. Proceedings of the Nutrition Society, 58(4), 791 – 798. doi.org/10.1017/S002966519900107X

Young AJ, Castellani JW. Exertional fatigue and cold exposure: mechanisms of hiker’s hypothermia. Appl Physiol Nutr Metab. 2007 Aug;32(4):793-8. doi: 10.1139/H07-041. PMID: 17622297.