A very real medical emergency has unfolded at a Las Vegas restaurant that offers "Bypass" burgers and "Flatliner" fries.

The doors to the Heart Attack Grill warn that eating off the menu may be hazardous to your health; and the warnings appear to have come true for one diner.

Amateur video has emerged showing a man being wheeled out of the Heart Attack Grill on a stretcher after a medical episode that restaurant employees say looked like, well, a heart attack.

The eatery's owner Dr Jon Basso, who is not a medical doctor, says he thought it was a joke when a waitress told him a customer was sweating and shaking.

"A nurse came to me and said 'Dr Jon, we've got a patient who's in trouble'. The gentleman could barely talk. He was sweating, suffering", he told a local news station.

Despite the serious nature of the incident, fellow diners reportedly thought it was just another part of the show.

"I actually felt horrible for the gentleman because tourists were taking photos of him as if it were some type of a stunt", Dr Jon said, "But even with our morbid sense of humour we wouldn't pull a stunt like that."

A Las Vegas fire spokesman confirmed paramedics were summoned to the restaurant on Saturday evening and a man was indeed hospitalised.

Since opening in October the restaurant has become infamous for its gut busting menu and the scantily clad 'nurses' who serve the food.

A single meal there can exceed 8,000 calories, and customers weighing in at over 350 pounds (159kg) eat for free.

Dr Basso says he heard the man is recuperating. His name and the medical condition he suffered weren't released.