Not to be scoffed at: Competitve eating is the world's fastest-growing hobby

What's the most dangerous thing you can do sitting down? It takes stamina and determination, and it tests your body to the limit. It brings fame and fortune to its top competitors, but claims as many lives as motorsport. Whitewater kayaking? Operating a crane? Or could it be competitive eating?

In the US, home of professional food consumption, the governing body Major League Eating (MLE) presides over a pastime that, it claims, is the world's fastest growing sport. Last month, 1.5 million people tuned in to ESPN to watch 23-year-old Joey "The Jaws" Chestnut defeat Takeru "Tsunami" Kobayashi in a tie-breaking eat-off at Nathan's Famous Fourth of July Hot Dog Eating Contest, the biggest event on the eating calendar. Chestnut walked away – gingerly, no doubt – with $10,000 in prize money.

Chestnut and Kobayashi are the Federer and Nadal of competitive eating. Between 2001 and 2006, Kobayashi, 29, won the Fourth of July contest at Coney Island, New York, six years in a row. In 2007, Chestnut beat his rival for the first time, breaking the Japanese champ's world record by eating 66 hot dogs (and their buns) in 12 minutes. When, a few days before the competition, Kobayashi announced that his vigorous training regime had resulted in an arthritic jaw, the news was briefly the lead story on the New York Times website. He recovered in time to compete, but could only stomach a personal best of 63 dogs.

Kobayashi retains some of his records, like the 41 lobster rolls he put away in 10 minutes, or the 17.7lbs of cow brains he once poked down in 15 minutes. But the young Chestnut's CV already reads like Godzilla's weekly shopping list. In June 2006, he ate 47 grilled cheese sandwiches in 10 minutes. In October 2007, he ate 103 hamburgers in eight minutes. And in April this year he ate 8.8lbs of tempura deep-fried asparagus spears in 10 minutes, at the Asparagus Fest in Stockton, California. His pee must have smelled funny for weeks.

The queen of the women's circuit is the diminutive Sonya "The Black Widow" Thomas, holder of numerous world records including hard-boiled eggs (65 in six minutes, 40 seconds), baked beans (8.4lbs in two minutes, 47 seconds) and oysters (46 dozen in 10 minutes). Thomas, who weighs in at just 105lbs prior to competition, is living proof that you needn't be obese to be a champion eater. In fact, she believes that her skinny build allows her stomach to expand with less difficulty than if it were surrounded by constricting adipose tissue; this is known as the Belt of Fat theory. Even the legendary Kobayashi weighs a modest 160lbs pounds.

Ryan Nerz is a spokesman for MLE, and the author of the competitive eating chronicle Eat This Book. As a non-competitor, he's still unsure of the motivations of most professional eaters. "America will make a sport out of anything," he says. "A lot of college fraternities and Wall Street banks hold eating contests, where they take bets on how many Big Macs they can eat in 10 minutes. Guys like to claim they're big eaters the same way they claim they're big drinkers.

"At the big eating events you have normal guys who get up and do this thing well, beat a bunch of people, and all of a sudden they have a camera shoved in their face. They get a whole new group of friends, a blog, a MySpace page, fans. It very quickly becomes their identity, and it transcends their former identity as a waiter at a pizza restaurant, an accountant or whatever."

The profile of a typical competitive eater has changed in recent years, from the overweight, blue-collar champions of old, such as Eric "Badlands" Booker, who has released two competitive-eating-themed hip-hop albums (Hungry and Focused and Hungry and Focused II: The Ingestion Engine) to a younger, slimmer, more middle-class competitor. There are now even two women in the world top 10, including Sonya Thomas.

MLE has made attempts to take the sport global, including holding a mince pie eating contest in Somerset in 2006, and a chicken satay eating contest at the first MLE Asia event in Singapore last week. Lup Fun Yau, 35, holds UK records for the eating of sugared doughnuts without licking one's lips (six in three minutes), and full English breakfasts (five and ¾ platefuls of fried food in 12 minutes). "It's a US sport," he says. "They take it far more seriously and the prize money is much bigger. The Black Widow and Joey the Jaws have made millions from it; they're in it for the money. But for people in England it's just about having a laugh, getting in the newspaper and having your 15 minutes of fame."

Kobayashi's jaw condition was a rarity, but intestinal injuries are expected to become more common as eaters develop training regimes as rigorous as an athlete's. Some top competitors regularly knock back large amounts of liquid (water, milk, or cola) to teach their stomachs to stretch. As well as the ever-present threat of gastric rupture, such treatment may damage their stomachs' digestive capabilities in the long term. "They're very close-lipped (pun intended) about their training methods," says Nerz. "They have to work on their stomach capacity. They have to work on being able to swallow large, barely chewed chunks of food. And some of them simply have natural talents – Joey Chestnut just has a really big mouth."

MLE maintains strict safety standards at all of its events, including the presence of emergency medics, and a lower-age limit of 18. But no one can legislate against unsanctioned competitions. Such episodes have led to a number of deaths. Adam Deeley, a graphic design student from Swansea, recently died after eating five fairy cakes in an impromptu contest. In January, a woman in California died after drinking almost two gallons of water in a competition sponsored by local radio – the prize on offer was a Nintendo Wii. And in 2002, a 14-year-old schoolboy from Japan choked to death after challenging his friends to a bread-eating race.

"Something like that happens every couple of years," says Nerz. "And we think that bolsters our whole reason for existing. Eating contests will occur whether or not they're organised by a governing body like MLE. So you may as well make sure they're organised with an emergency medical technician at every contest, and with a group like us who'll monitor the safety of each contest. The reason each of our events is only about eight to 12 minutes long is that, not only will the audience and the media reach a limit of what they want to watch, but also the competitors won't cause themselves any distinct damage."

It says something about the decadence of the developed world that we should celebrate the swallowing of 47 glazed doughnuts in eight minutes (by Eric Booker), while the world food crisis rages just outside the stadium gates. Then again, as Nerz argues, motorsport also has an ethical case to answer: "[But] people don't complain about Nascar wasting gas."

The competitive eaters' hall of fame

Mayonnaise: Four 907g bowls in 8 minutes - Oleg Zhornitskiy

Mince pies: 6 pies at the Wookey Hole Big Eat in Somerset in 10 minutes - Sonya Thomas, 29 November 2006

Nigiri sushi: 141 pieces in six minutes - Timothy Janus, 11 April 2008

Peanut butter & jelly sandwiches: 42 sandwiches in 10 minutes - Patrick Bertoletti, 8 August 2007

Spam: 2.72kg of Spam in 12 minutes - Richard LeFevre, 3 April 2004

Pork ribs: 3.81kg in 12 minutes - Joey Chestnut, 16 July 2006

Pigs' trotters: 1.31kg of pigs' trotters in 10 minutes- Arturo Rios Jr, 23 June 2007

Peas: 4.31kg in 12 minutes - Eric Booker

Shrimps: 2.26kg of spot shrimps in 12 minutes - Erik Denmark, 22 September 2006

Jalapeños: 177 pickled jalapeño peppers in 15 minutes - Patrick Bertoletti

Waffles: 29 waffles in 10 minutes - Patrick Bertoletti, 7 October 2007

Lobster: 44 Maine lobsters (5.13kg of meat) from the shell in 12 minutes - Sonya Thomas, 13 August 2005