Douglas became the third straight U.S. athlete and first African-American to win the all-around title.
Gabby Douglas admitted indulging in post-Olympics fast food to the wrong person: First lady and healthy eating advocate Michelle Obama, who teased the gymnastics champion.
"You're setting me back, Gabby," Obama told Douglas.
"Sorry!" replied the 16-year-old athlete, who confessed to chowing down on a McDonalds' breakfast sandwich after winning two gold medals at the just-ended London Olympics.
But she impressed Mrs. Obama and Leno with a detailed description of how, starting at age 6, she learned to navigate the 4-inch-wide balance beam.
The host wanted to know if the dream of winning matched the reality.
"I think it's very different, and when I mean 'different' it's in a better way," Douglas replied. "I mean, I never thought I would be doing the show with the first lady, or even you, Jay."
Leno started to reply, when Mrs. Obama jumped in.
"Even you too, Jay!" she said.
Douglas became the third straight U.S. athlete and first African-American to win the all-around title. She and her teammates gave the U.S. its first Olympic title in women's gymnastics since 1996.
On another sports-related topic, Leno put the first lady on the spot about what he called "this whole kiss cam thing" at a recent basketball game.
Last month, she and President Barack Obama were at a U.S. Olympic men's basketball team exhibition game in Washington when the arena's "Kiss Cam" panned to them. She appeared to shake her head "no" to a smooch.
That's not what happened, Michelle Obama told Leno.
"I had just walked in and sat down, and I just saw my face on the Jumbotron. And I'm still a little embarrassed. ... I didn't see the 'kiss cam' part," she said.
After the couple was booed, daughter Malia set them straight.
"She was just disgusted with us," Obama recounted. "She said, 'Why didn't you kiss?'"
The 13-year-old quickly proved her skills as a problem-solver.
"I've arranged for you to get another chance on the kiss cam," she told her parents, according to the first lady. The president delivered, giving the first lady a big kiss on the lips and adding a peck on the forehead for good measure.
Then Leno turned serious, asking Obama what she's proudest of in her husband's first term.
"Truly, health reform," she said. "That's no longer an issue for Americans, you can't be denied coverage because of pre-existing conditions."