A woman was found living in a Utah national forest after disappearing nearly 6 months ago. A survival expert explains how she may've done it.

• Five and a half months after disappearing, a woman was found living in a national forest in Utah.
• Officials said she had few supplies and little food but was "resourceful" and wanted "solitude."
• A survival expert told Insider how the woman might've been able to survive the extreme conditions.

In November, when Forest Service officials in Utah were preparing to close up parts of the Spanish Fork Canyon for the winter, they discovered a seemingly abandoned car in a campground parking lot.

A search-and-rescue crew set out to look for the woman the car belonged to but came up dry. Detectives spent months trying, without success, to find and contact her family. Five and a half months passed without any sign of her.

Then on May 2, a nonprofit aerial search group that was conducting a new search for the woman had a drone crash on the first sweep. When the group went to retrieve the drone, the group members stumbled across a tent. Suddenly, the tent unzipped, and the woman they had been seeking poked her head out.

"Our assumption was, and we've had circumstances like this a lot of times in the past, that we would probably have somebody find her in the spring and that she would have died," Sgt. Spencer Cannon of the Utah County Sheriff's Office told Insider. "So we were as shocked as anybody."

Cannon said the woman told them she went to the Uinta-Wasatch-Cache National Forest intentionally because she wanted solitude.

"She certainly accomplished that," he said.

But not without jeopardizing her health.

The woman, who is 47, had lost a lot of weight and was in rough shape when officials found her. She had little equipment beyond a sleeping bag and tent and had brought just a small amount of food with her, claiming to have subsisted on grass and moss. Cannon said he didn't think she would've made it many more weeks in her condition.

Some were surprised she was able to survive for that long. Cat Bigney, a survival expert who has consulted for the likes of Bear Grylls and National Geographic, was not one of them.

If you can't maintain a safe core body temperature, 'that's when you'll die'

"If you think about our existence as a species on the globe, most of our lives, we lived that way," Bigney told Insider. "It's something that's really part of our DNA."

Bigney, who has taught at the Boulder Outdoor Survival School for decades, pointed out that plenty of humans around the world and in the US, particularly on some Native American reservations, still lived without heat, electricity, or running water. She was impressed by the Utah woman's story, but her survival knowledge helped her understand how it was possible.

In this situation, Bigney said, thermoregulation, or the ability to maintain a safe core body temperature, would be the biggest survival issue. If your core temperature gets too far above or below 98.6 degrees Fahrenheit and stays there for too long, "that's when you'll die," she said.

The area of Utah where the woman was found experiences double-digit below-zero temperatures in the winter, as well as significant amounts of snow, but there are lots of ways a person can regulate body temperature.

She may have been wearing really good clothing. She may have used an external heat source, like fire. Or she may have just used what was around her to create insulation and prevent the loss of her body heat.

For instance, Bigney said, if you're sleeping on the ground, it can "suck the heat right out of you." Instead, you can collect branches, leaves, or even pine needles to create space and insulate yourself. She said she'd even been able to do this without a sleeping bag.

"I've slept in big piles of leaves, and just kind of wiggled in the leaves in snowstorms, just to have that insulating effect holding in my core body temperature," she said, adding that you can also stuff your clothing with foliage. "Anything that's going to create some dead air space to keep that heat in."

'We can fast for a month at a time'

Another question concerning how the woman survived revolved around food. Cannon said the woman had brought a small amount of rice and beans with her and was given some food by other campers she encountered early on, but she also told officials she subsisted on grass and moss.

Bigney said eating grass or moss was dangerous, pointing out that humans couldn't actually digest grass the way many ungulates such as cows, goats, and buffaloes do.

"She may have received some micronutrients from grass" just by chewing it, Bigney said. But if she swallowed it, she may have gotten sick. Regardless, grass and moss couldn't provide a substantial source of calories.

But Bigney said humans could survive, albeit not comfortably, on small quantities of food for extended periods of time.

"We can fast for a month at a time," Bigney said. "It's pretty extreme, but our bodies are built for that."

Most likely, the woman was able to survive by rationing out the small amount of food she brought with her. Still, the lack of food had also clearly taken a toll on the woman, who had lost a lot of weight by the time she was discovered.

Bigney said people in situations like that might also experience hair loss or issues with their teeth because of a lack of nutrients. And at some point, extended bouts of extreme fasting or starvation can lead to irreversible physiological damage.

The river water may have been relatively clean, but not without significant risk

The third major survival concern in this woman's situation would've been water, which humans can go without for only about three days. Cannon said the woman had an ample water supply close to where she set up camp and was drinking straight out of a flowing river.

"You hate to think of any outdoor water supply as being reliable and clean," he said, adding that there were "more risky supplies than that one."

Especially in the winter, with little human foot traffic and fewer animals urinating and defecating nearby, it's possible the water was relatively safe, though certainly not without risk.

Bigney, who grew up drinking untreated water in Utah's Wasatch Mountains, said it's also possible that if the woman grew up in the area, "she could have microflora in her gut that was more compatible" with the water. But she said it's also possible the woman might now be suffering from parasites.

One common parasite, giardia, is found in water that has been contaminated with feces from infected people or animals. It can cause diarrhea, fatigue, and cramps. According to the Centers for Disease Control and Prevention, some people infected with giardia have no symptoms.

But because of the significant risks of drinking untreated water, the CDC recommends backpackers and campers properly treat any water taken from springs, lakes, or rivers before drinking.

'The biggest thing that will kill you in a survival situation is to panic'

Though it's hard for some people to imagine how they would survive in such extreme conditions, Bigney said it's not as complicated as it seems. While having some survival knowledge helps, she said you don't necessarily need a doctorate on the subject.

"The truth about survival is just being resourceful and innovative," she said. "The biggest thing that will kill you in a survival situation is to panic."

She said the best survivalists in the world weren't necessarily the people who could reliably build the best fire but rather those who have awareness of their surroundings and are able to remain mentally sound.

"I've traveled all over the world and been in environments that I know nothing about," she said. "It goes back to, what things can kill me, and how quickly, and what are my resources here, and what do I need right now."

Officials had described the woman in Utah as "resourceful" but also said they had reason to believe she had struggled with mental illness. Details about who she was or why she did it have been scarce, but Bigney was also impressed by her apparent resourcefulness and the fact that she had chosen to go out in the first place.

"I think it could be a really good thing for people to unplug and get away and do a solo excursion," she said. "But there has to be some sort of balance there. You don't want some sort of awakening nature time to become a suicide attempt."

Have a news tip? Contact this reporter at kvlamis@insider.com.