FUEL for the Long Haul: Conserving Calories to Survive

FUEL for the Long Haul: Conserving Calories to Survive

In just a matter of minutes, a quick hike up a mountain can lead into a life-anddeath struggle for survival. Mother Nature is unforgiving when it comes to the circle of life.

Jessica Crandall, dietitian and spokesperson for the Academy of Nutrition and Dietetics, had a two hour bike ride in the Fort Collins, Colo. area turn into an eight hour ride because of road closures. Worse yet, she remembers a family hike on the San Carlos Trail in Beulah, Colo., as a child that went wrong due to a map miscalculation that resulted in being lost, some injuries, and hunger. The ordeal lasted for 24 hours until search and rescue found them.

“It was not the trip you’d ever want to go on, so planning and preparing is key,” Crandall said. In a survival situation, even if you have planned ahead with food and water, you still need to be smart about how you use it.

Calories Count

“When you know…you’re going to be gone for a long period of time, I would just kind of take an inventory of what I have and plan for the worst,” Crandall said.

She tends to pack for 24 to 48 hours, about three times more than what she needs. This includes spacing out food.

Dried fruit, which travels well, is a wonderful source of carbohydrates, whereas nuts, such as almonds, walnuts and pistachios are a great source of protein

“I would plan for eating every four to six hours a meal [designed to] help keep my energy level stable,” she said.

Examples include eating a serving of nuts, such as almonds, walnuts and pistachios, with a serving of dried fruit. The nuts would be the protein and the dried fruit would be the carbohydrate source. Another option is eating tuna or jerky for protein. Crandall recommends a serving size of two to four ounces.

Crandall says people can live up to 21 days without food, but some die sooner because they don’t have weight reserves. Most people won’t survive more than three to four days without water, she says, but there are reports of some individuals lasting up to seven days.

What Happens When You Run Out?

If you run out of food, depending on the situation, going out and finding it might not be the best idea, according to Tony Nester, founder of Ancient Pathways, an organization that offers courses in wilderness survival, primitive skills and bushcraft.


“We have this basal metabolic rate that we humans have to meet every day; it’s about 1200 calories a day for the average adult,” Nester said. “If I’m putting out more calories than I’m getting back then that’s not going to be a good situation.”

A handful of beef jerky (roughly 10 ounces) has about 1,200 calories, by far one of the best calories-toweight trail foods.
A small can of tuna has about 200 calories in it, which you will burn off in about an hour’s worth of walking.
If you’re in the desert without a lot of options for food, fast to stay alive longer.

If that’s the case, Nester says, rather than trying to find food by hunting or looking for berries (which you need to be trained on what you can eat safely anyway) “you’re better off holing up in your shelter and fasting because your body will tap into both its protein and fast reserves. That’s key because you’ll last about 25 percent longer than the person who is just going out and getting the occasional grub squirrel or cricket and not exceeding that 1200 calories a day.”

If you put out more calories than you take in, your body will start consuming its lean muscle mass and fat, says Nester, who has provided survival training for actors such as Emile Hirsch for “Into The Wild.” People can go 30 to 40 days without food in an outdoor setting, with exceptions of people lasting longer, Nester said.

“It is possible under the right conditions,” he said. Water is a different situation, however, and different strategies are needed to prolong life without it.

Setting a trap is a passive way of harvesting food. It requires little physical effort on your part, therefore conserving energy

If you end up needing to feed yourself in the wilderness and you don’t have anything to eat, there are two approaches: active and passive. “Active is where you’re moving across the land actively looking with a bow and arrow or a rifle (or other weapon) looking for deer or elk,” said Tony Nester, a survival teacher. “Passive means setting up snares and traps and leaving them overnight. That system (passive) is way more calorie-effective and way more efficient from a physiological standpoint.”

How to Think of Water

Consuming too little water causes dehydration and the person suffering from it in hot weather will eventually die from heat stroke. But if someone drinks too much, this will cause “diluted blood sodium or hyponatremia,” says Tom Myers, who has worked for 25 years at the Grand Canyon Clinic as a physician. If left untreated, that also can lead to death.


So, the physician says, “only drink when you are thirsty.” “The deficit must be eventually made up and only builds,” he said. “In survival situations when water is scarce or limited, minimizing eating or not eating at all (especially salty food) until sufficient water is found can buy time and help make water “last longer.”

This is because no water is used for digestion, he explains, and this can probably be done only for a few days maximum.

“It is a trade off, as we need food for fuel,” he said. To slow “excessive evaporation and water loss from the skin” leading to dehydration, cover up with light colored, loose fitting and breathable clothing, such as cotton.

“Wet your head and shirt, when you can, even with bio-contaminated water,” he said. “It helps with evaporative cooling to keep core temperature down, and helps with mood by negating some of the oppressive feelings of heat.”

Myers recommends estimating how long a hike may take from start to finish and to “factor in the air temperature.” He cites instructions from Edward Adolph’s “Physiology of Man in the Desert”: 1/2 liter per hour at 80 F; 1 liter per hour at 100 F; and 1.5 liter per hour at 110 F.


“In other words, fluid needs triple from 80F to 110F,” he says. “And fluid needs are less at cooler temps.” If it is a matter of life or death, Myers recommends people should drink biocontaminated water.

“Water-borne illnesses usually take a week or longer to kick in and these are typically easy to treat,” he said. Water is a different situation, however, and different strategies are needed to prolong life without it.


Editor’s Note: A version of this article first appeared in the July 2015 print issue of American Survival Guide.

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