Washington (CNN) - Potential 2016 presidential candidate Chris Christie may be able to take the punch lines about his waistline. The popular New Jersey governor made light of his weight in an appearance on "The Late Show with David Letterman" Monday night.
"I'm basically the healthiest fat guy you've ever seen in your life," Christie joked.
But one medical expert on presidential health cautioned Christie's obesity is no laughing matter.
"I'm worried he may have a heart attack. I'm worried he may have a stroke," former White House physician Connie Mariano, M.D. said in an interview with CNN.
And, in fact, Christie acknowledges as much as recently as Tuesday when asked about his Late Show appearance.
"I have been remarkably healthy. My doctor continues to warn me my luck is going to run out relatively soon. So, believe me, it is something that I am very conscious of," Christie said.
Mariano, who served nine years as a doctor in the White House medical unit said Christie's obesity would certainly become an issue should he run for the presidency in 2016. She warned a future President Christie could suffer from potentially deadly complications from diabetes, sleep apnea, and heart disease.
"It's almost a like a time bomb waiting to happen unless he addresses those issues before running for office," Mariano said.
During the 1990's, Mariano helped then-President Bill Clinton in his own struggles with losing weight. She recalled how Saturday Night Live once lampooned Mr. Clinton as an insatiable junk food addict, pounding Big Macs from McDonalds.
After Clinton stumbled on some steps and tore a quadriceps tendon, Mariano said she worked with the White House chef and a personal trainer to help the president lose nearly 30 pounds.
All of that explains why Mariano winced when she saw Christie munch on a donut while waiting for Letterman to ask a question to the delight of a studio audience Monday night. She said her words of caution should not be viewed through any partisan lens.
"I'm a Republican. I like Chris Christie. I want him to run. I just want him to lose weight," Mariano said. "I'm a physician more than I'm a Democrat or Republican. And I'm worried about this man dying in office."
In Union, New Jersey Tuesday following a meeting with Hurricane Sandy victims, the 50 year old governor also told reporters he has a plan to get in shape.
"Be assured there is a plan. Whether it's successful or not, you'll all be able to notice," Christie said.
The governor shrugged off the notion that he is not taking his health seriously.
"The idea that somehow, you know, I don't care about this – of course I care about it. And I am making the best effort I can," Christie said.
Christie's office tweeted out the comments in a video link to the governor's followers on Twitter Tuesday afternoon.
Mariano said Christie could set a good example for the nation's growing population of obese children and teen-agers.
"He could actually save lives out there if he turned around and did something with his weight and became healthy," Mariano said.
After serving both Democratic and Republican presidents, Mariano said she is offering her medical advice to Christie in large part because he remains a strong potential contender for the White House.
"I'm dead serious," she said.