As Zack Buck, a student at Southeast Missouri State University, spent three weeks in South America for the Discovery Channel's "Naked and Afraid" television series, he wondered whether he could endure the last several days.

Buck, a 26-year-old from St. Louis, and a woman he'd never met were dropped off naked in Guyana, on the Caribbean coast of South America, last October.

An episode documenting their experience will air at 9 p.m. Sunday on the Discovery Channel.

Guyana is 80 percent forest, he said, but the pair was left in the savanna, where shelter, food and water are scarce.

Buck is no stranger to the outdoors. He spent two summers and most of last year in Utah, where he worked with at-risk youths in the state's western desert. There, he learned and taught survival skills, from building a shelter to creating fire by hand-drilling embers with sticks.

Buck said he's a fan of reality survival shows such as "Dual Survival." And when a friend who also was on "Naked and Afraid" suggested Buck audition, he went for it.

When he told his family and wife the news, they weren't surprised, Buck said.

"My whole family knows I kind of do some crazy endeavors," he said.

Buck went to Southeast because of an opportunity to play football.

He walked onto the team as a defensive end in 2007 and played through 2009.

He plans to finish three classes at Southeast to earn a Bachelor of Science in recreation with an emphasis in outdoor leadership. He hopes to run survival-based clinics in St. Louis and Cape Girardeau.

In its fourth season, "Naked and Afraid" follows two people, a man and a woman, who are dropped off naked at a remote location somewhere in the world, challenging them to survive for three weeks without quitting.

Buck said his partner's personality differed greatly from his own, and he found himself biting his tongue to keep the peace.

"But we never really fought," he said. "We were very civil, even if we were two very different people."

Each person can bring one personal item from home. Buck said he brought a custom knife made by a blacksmith in Indiana.

Each day, Buck said he would have to decide whether to go on a hunting trip and at what time.

If he didn't get anything, it would be a lot of wasted calories.

"You have to conserve energy while being smart about how you expend energy," he said.

And, of course, being naked added another complication, he said, especially with a long hike the first day through tropical grassland.

"Being naked, you're exposed to getting sunburned," Buck said. "The first chance I found mud, I put it all over me like sunblock and kept going."

He also had to be careful not to step on thorns or anything else that could hurt his feet.

But the most difficult part, he said, was the lack of sleep. Flies and gnats swarmed him during the day, and at night, mosquitoes were a constant battle.

"You wake up and hear these crazy sounds," he said. "The howler monkeys sound like demons in the night or something. When the sunlight hits, you've got crazy birds making sounds. It's hard to do things and have energy when you can't replenish that sleep at night."

Then, daylight brought extreme heat.

"All day long was just about 100-degree weather," he said. "You couldn't move around too much midday, because you really didn't want to go in the sun. It'd really take it out of you."

By the last couple of days, Buck had lost 28 pounds.

He had a 103-degree temperature, he said, and couldn't feel his fingertips.

"When I would stand up to get water, I would black out if I would stand all the way up," he said. "By the end of it, I was super excited that I was leaving, but I couldn't really show much of it, because I was so exhausted from being sick, as well as having that malnutrition kick in."

When he reached a hotel back in the United States, Buck said, he ordered a bucket of fried chicken and had a tub of chocolate ice cream.

"Needless to say, I was very happy and appreciative of what was in front of me," he said.

klamb@semissourian.com

388-3639