Japanese competitive eater Takeru Kobayashi, the six-time Nathan's Hot Dog Eating Contest champion, has announced his retirement from the sport due to rising health concerns.

"I’ve decided to retire from competitive eating. It’s all I've done for the last 20 years," Kobayashi, 46, announced in Netflix's "Hack Your Health - The Secrets of Your Gut," a documentary film that explores how food, the digestive system and gut health relates to overall well-being.

Kobayashi said decades of overeating for sport has left him with no appetite or no sensation of fullness, which his wife Maggie James said has caused Kobayashi to go days without eating anything at all.

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James said her husband feels his body is "broken."

"I hear people say they’re hungry, and they look very happy after they’ve eaten. I’m jealous of those people because I no longer feel hunger," Kobayashi said in the documentary. "I hope to live a long and healthy life."

Takeru Kobayashi: 'I've eaten 10,000 hot dogs' in career

Kobayashi jumpstarted his career in 2000 during an appearance on the Japanese variety show "TV Champion," where he consumed 16 bowls of ramen in one hour. He set a world record at the 2001 Nathan's Coney Island Hot Dog Eating Contest, held annually on July 4, by eating 50 hot dogs in 12 minutes. (The previous record at the time was 25⅛ hot dogs). He won the Mustard Yellow Belt six consecutive years from 2001 to 2006.

"I'm sure that I've eaten 10,000 hot dogs since the beginning of my career," Kobayashi said in the film.

Kobayashi does not just eat hot dogs. He's held world records over his career with different foods, ranging from Buffalo wings, lobster rolls and cow brains to hamburgers, tacos and pizza. The list goes on. 

"I am Japanese but I've eaten like an American. I think that's what damaged my body," he said. "I overeat because I’m a competitive eater. ... When you eat too much, you don’t savor the taste or fully enjoy the smell of the food. You ignore you body’s signals, like fullness."

In order to prepare for competitions, Kobayashi said he would spend months expanding his stomach with food.

"You have to gradually build up your gut by eating larger and larger amounts of food, and then be sure to work it all off so body fat doesn't put a squeeze on the expansion of your stomach in competition. I start my regimen about two months before a big competition," he said in 2004.

Kobayashi's brain affected by competitive eating

Kobayashi underwent multiple tests during the documentary to diagnose his lack of appetite and reduced sense of smell. Doctors and scientists determined that Kobayashi's chronic overeating has affected his nervous system and that his brain is still trained to think he's competing or eating highly processed foods, despite stepping away from competition.

"I used to crave cakes and curries when I was little. I don't feel that joy about eating anymore," he said. "It’s scary to think that the brain and gut are so closely related. It makes me want to be more careful with what I eat."

Although Kobayashi won't be competing at Coney Island on the Fourth of July anymore, he's not giving up hot dogs completely. Kobayashi said he's on a mission to "create a healthier hot dog" that features traditional Japanese ingredients.

"What’s influenced me more than competitive eating is the hot dog," he said. "I am worried about what my next step will bring, but I am also excited about my future."