Thursday afternoon, Demong became the first American to even win a gold medal in Nordic combined. That night, his fellow American Olympians selected him to carry the country's flag at the closing ceremonies. Demong, who also proposed to his girlfriend Thursday night, called it "a whirlwind of a day."
ABC News caught up with Demong a few weeks before the games to learn his secret to success.
"Obviously the food at some of the hotels we stay at in these small towns is a little bland," Demong said. "So we bring a lot of peanut butter for packing lunches on race day, and hot sauce to spice up some bland food."
Demong also brings his own coffee and a press, and he's outright giddy if he finds eggs and bacon. In January, he was in France and was often served plain pasta -- the perfect time to use the Tabasco and Cholula hot sauces to add some flavor.
"If you stay at a one-star or two-star hotel, you get one- or two-star food," he said. "At this point in my career, I've learned to adjust"
At the Olympics, there are plenty of food options so finding food you like isn't the challenge. The biggest problem with the Olympic Village, Demong said, is the "massive amount of food" and learning how to craft a healthy diet.
This year's games in Vancouver mark Demong's fourth Olympics. He competed in Nagano, Japan, Salt Lake City and Torino, Italy, but did not medal.
The United States doesn't have a great history in Nordic combined, a mix of cross country skiing and ski jumping. But this year, the U.S. came into the Olympics with three world champions, including Demong, on the team.
"It's been a long road for U.S. Nordic combined. We've never won an Olympic medal before," Demong said before the games.
That finally happened on Feb. 14 when American Johnny Spillane won silver in the sport's first event in Vancouver.
Demong had a disappointing ski jump and came into the cross country part of the competition a very distant 1 minute and 18 seconds behind. He made an amazing comeback, finishing less than 18 seconds behind the leader.
"He looks better than anybody right now," one TV commentator said of his performance, halfway through the race. Demong ultimately fished sixth.
Then Tuesday afternoon, Demong gave an impressive show in the four-man team relay.
The American team was 14.1 seconds, behind the leading Austrians when Demong took over the relay for the final 5-kilometer leg. After 1.7 kilometers, Demong narrowed the Austrian lead to 7.3. By 2.5 kilometers that lead narrowed to 2.2 seconds. At 4.2 kilometers into the race, Demong closed that gap to just six tenths of a second. But in the end, he fell back and finished 5.2 seconds after the Austrian team, leading to a silver medal.
And then finally on Thursday, in his last appearance in the Vancouver Winter Games, Demong won gold, pulling off a victory after starting off 46 seconds behind. Fellow American Johnny Spillane won silver. It was the first gold medal ever for the United States in Nordic combined.
The Training Schedule of an Olympiad
ABC News caught up with Demong a few weeks ago as he trained at the White Pine Touring Center near his home in Park City, Utah. It was early in the morning, the snow was falling fast and a heavy snow overnight was burying Demong's cross country skis. But none of that stopped him from racing up and down the hills.
"I enjoy my training. It's my lifestyle. I don't take time off," he said. "Even when I'm on the beach on vacation, I tend to go for a run every day. It just helps me feel better."
Between cross country skiing and the ski jumps, he spends about four to five hours a day on skis. Add in other land-based training and it's a full schedule.
Nordic combined is a small sport, and the American team has lived together in the same city for years, first in Steamboat Springs, Colo., and in Park City since 2002. The idea is that the novice and veterans train together and push each other.
"It allows us to bestow our knowledge on the younger guys," said Demong, who at 29 is considered a veteran.
Park City's 7,000-foot elevation is also a plus.
"One of the reasons to live up in the mountains as an endurance athlete is to utilize altitude as a training mode and to increase your aerobic capacity," Demong said.
1980 Olympics Spur Passion
Demong grew up in upstate New York and was cross country skiing by the time he was 5.
"Cross country is one of the easiest winter sports to do. All you need is a pair of skis and a little bit of snow. Growing up, I did a lot of skiing in our backyard," Demong said.
Just two years later, he met Larry Stone, a ski jump coach who showed him and other skiers a rough video, set to music, about ski jumping. He was hooked and started training at Lake Placid, N.Y., the site of the 1932 and 1980 Winter Olympics.
It seemed like a natural fit. Demong was born a month after the 1980 Olympics and people upstate -- and across the country -- were still rejoicing over the U.S. hockey team's surprise win against the Russians, the so-called Miracle on Ice.
Olympic Ski Jumps
Demong grew up driving past the two massive ski jumps that sit close to the highway leading into Lake Placid and and remembers seeing those jumps "looming over the village" and feeling the Olympic lure.
"It's the worst place in the world to grow up, because you stare at those towers your whole life," he said. "I was always sort of immersed in Olympic feeling."
For a young athlete in the days before the Internet, Demong said, "it was like winning the lottery to find some video of somebody jumping on an international level."
Today, the sport has a big online following, and aspiring athletes can track the pros' progress daily.
"I get Facebook messages every day from 13-year-olds saying, 'good job,'" he said.
Demong said there is nothing quite like flying off a ski jump, but that first jump can be very intimidating.
"When I was young, I was really afraid," he said. "It took me a few days of standing at the top the run before I actually had the nerve to push off the bar."
Even today, there is "always a flutter of the heart" before taking a jump.
"It really feels like flying," said. "We travel upwards of 450 feet in the air, most of it horizontal, actually. You feel the pressure of the wind on your skis, on your body and you just lay on it as if you were a human hang glider."
Demong said the Olympics are completely different than any other competition.
"In one way, it's the same in that you have the same competitors, the same countries, the same people and the same event, but on the other way you have a whole bunch of added pressure to do well in the once-in-a-lifetime or once-every-four-years event," he said.
More friends and more media show up for the events. But he said athletes also get to meet up with other athletes from different sports from around the world.
"For two weeks, the whole world seemingly turns to one place and pays attention to one thing. It's a pretty special experience," Demong said. "My favorite part is being about to compete for Team USA. It's a greater feeling to have the whole country behind you, to be part of a 300-member athletic squad going to represent your country."