It wasn't a personal best for the 27-year-old nicknamed Jaws, but it was enough to out-eat second-place finisher Patrick Bertoletti by nine wieners. Chestnut, of San Jose, Calif., won $10,000 and the coveted mustard-yellow belt.
"I feel great!" he said after the contest, adding that he was going to drink a lot of water and avoid hot dogs for a few days.
Chestnut started at a blistering pace but couldn't beat his own record of 68 "because I kept messing up," he said, pausing for a burp. "Excuse me," he told reporters squeezed around him.
Bertoletti, of Chicago, won $5,000, and third-place contestant Tim Janus, of New York, won $2,500.
This year, for the first time, the annual contest in front of Nathan's Famous fast-food stand was broken into two divisions, one for men and one for women.
Sonya Thomas, known as the "Black Widow" of competitive eating, won with 40 downed dogs, earning her $10,000 and her own pink champion's belt.
"I'm so happy!" said Thomas, of Alexandria, Va.
She started out neck-and-neck with second-place finisher Juliet Lee but later pulled ahead.
"I looked over, and I said, `No way!' But I have to focus myself, because I cannot keep up with her now," Thomas said.
Instead, she preserved her biggest jolt of energy for the winning end.
Lee, of Germantown, Md., ate 29? wieners, and Stephanie Torres, of Las Cruces, N.M., downed 28?.
Both Thomas and Chestnut broke world records in 2009, he with 68 and she with 41.
Chestnut's chief rival, Takeru Kobayashi, stayed away from the contest this year, staging a separate competition where he ate 69 dogs in 10 minutes - which would have been a world record.
The slim Japanese champ held the record for hot dog eating from 2001 to 2007. After refusing to sign an exclusive contract with Major League Eating, the fast-food equivalent of the NFL, he was banned from the competition last year.
But he showed up anyway, wearing a T-shirt that said "Free Kobi," rushed the stage and was arrested. Charges of disorderly conduct, resisting arrest, obstruction of property and trespassing were later dropped.
This year, the Japanese native nicknamed the "Tsunami" held the unofficial contest from a rooftop on ritzy Fifth Avenue, eating near a giant plasma TV airing the official competition live.
The annual spectacle on Coney Island draws tens of thousands of holiday revelers, watching as contestants shimmy, slither and bounce as they dip hot dogs in water and cram them down their throats.
For some, it's a painful reminder of excess - especially as the U.S. battles a growing obesity problem. The American Medical Association opposes competitive eating, saying it's harmful to the human body.
"I am disgusted watching them, in a world where we try to do our best not to overeat and become obese," said contest viewer Eve Harrison, 42, a New York City art dealer who lives in North Salem, N.Y.
And hot dogs aren't exactly the healthiest of choices. In addition to beef, they include salt and various food additives, including sorbitol and hydrolyzed soy.
But the competitive eaters are quite trim. Chestnut is over 6 feet tall and a muscly 218 pounds, and Thomas and her rival Lee weighed in at barely 100 pounds each.
"I don't think it's supposed to be seen as anything other than a satire," attendee Eli Pearlstein said of the competition.
And for one scorching summer day, it's a good fit for that most American of places - kitschy Coney Island.
Joining the 2011 men's lineup were three new contestants flown in from China - the next big target market for the Nathan's brand.
Master of ceremonies George Shea acknowledged that the eating contest is one big sales gimmick - for Nathan's products. It's been a wild marketing success.
In the past seven years, Nathan's revenues have soared by more than 90 percent, with more than 450 million hot dogs sold annually and the value of its publicly traded shares tripling. Nathan's donated 100,000 hot dogs to the food bank before the competition.
In the end, the contest is less about food than hunger for money.
Major League Eating organizes about 100 eating events for such varied foods as oysters, cheesesteak and asparagus - sponsored by brands like 7-Eleven, Roy Rogers, Krystal and Harrah's.
On Monday, visitors enjoyed new Italian-made amusement park rides that are part of Mayor Michael Bloomberg's vision for the redevelopment of the People's Playground on Coney Island. The seaside neighborhood served as an escape for generations of Americans, but fell into seedy disrepair in recent years.
The first hot dog was sold here by German-born butcher Charles Feltman, but it was his Polish-born employee, Nathan Handwerker, who really scored by opening his own business in 1916 - Nathan's Famous.
According to local lore, the Nathan's contest was started by immigrant men arguing about who was most American. They settled their dispute by trying to out-eat each other. Irishman Jim Mullen won with a paltry 13 dogs.
Major League Eating: http://www.ifoce.com