TRENTON, N.J. (CBSNewYork/AP) -- New Jersey Gov. Chris Christie said Tuesday he underwent gastric band surgery three months ago to try to lose weight.
Christie had the surgery, in which a band was placed around his stomach to restrict the amount of food he can eat, on Feb. 16.
The governor decided to have the procedure after turning 50 in September.
Speaking at a news conference, Christie took issue with a reporter asking why he didn't disclose the surgery sooner.
"In terms of keeping it secret, it's nobody else's business," Christie said. "If asked about it, I wouldn't have lied about it. But it's nobody else's business but mine."
The father of four said he's already lost weight -- reportedly a total of 40 pounds -- from the procedure.
He said he was motivated by concerns over his health, not future political aspirations.
"It's not a career issue. It is a long-term health issue," Christie said. "What spurred me to do it was I turned 50 years old. I got confronted with your own mortality as I started to age. This is about my kids, Mary Pat and me."
Christie got fired up at the suggestion that his career was the motivation.
"It may sound odd. This is a hell of a lot more important than running for president," he said. "This is about my family's future and that's more important to me than running for president."
Gov. Christie Discusses Weight Loss Surgery, Says Decision Not Career-Based
"My decisions about anything to do with my career are based upon what I think is best for me and best for my family. Whatever size I happen to be when I have to make decisions about to do next in my career, I doubt that'll play any role or effect in what I decide to do," Christie continued. "I think I made that pretty clear to you guys over time. It's not a career issue for me. It is a long-term health issue for me and that's the basis upon which I made the decision. It's not about anything other than that."
Christie has never disclosed his weight, but joked about his size during a February appearance on "The Late Show with David Letterman," pulling out a doughnut and saying his girth was "fair game" for comedians who have made fun of his size for years.
"From my perspective, if the joke is funny, I laugh – even if it's about me," Christie told Letterman. "If it's not funny, I don't laugh. But I've never felt like it was anything that really bugged me all that much, no."
One day after his appearance on Letterman, Christie discussed his struggles with his weight with CBS 2's Christine Sloan.
"So far, up to 50 years old, I've been remarkably healthy. My doctor continues to warn me that my luck is going to run out," said Christie.
Days later, Christie had the surgery. He said the operation lasted 40 minutes and he was home the same afternoon.
Some say his decision to undergo surgery may not have been entirely motivated by health.
"He went in and had outpatient surgery on Presidents Day weekend to make sure everything is sufficiently parallel here," CBS News political director John Dickerson said on "CBS This Morning." "You know, remember that [former Mississippi Governor] Haley Barbour said, 'If I lose 50 pounds, it's because I'm running for president or I got sick.' Chris Christie in typical fashion is cutting to the chase doing this."
Kimberley Fletcher told CBS 2's Hazel Sanchez she can relate. Weighing 300 pounds two years ago, Fletcher had a lap band procedure to lose weight for hip surgery.
She has since lost 136 pounds, and said Christie should be feeling the benefits of his lap band now.
"I think he's starting to be a little more energetic; not breathing so heavy, because I had sleep apnea also and mine is gone," she said.
Meanwhile, political analysts said shedding pounds and looking more like the athlete he once was in high school will help Christie politically, but noted there are some downfalls.
"I think he's definitely preparing himself. I don't know that this surgery has much to do with that, I think he's certainly preparing to run in 2016," Seton Hall University political professor Matthew Hale told Sloan on Tuesday.
"What could potentially hurt him is if doesn't stick to it. He has the surgery, he loses the weight -- that's going to be a story line, every pound is going to be the story line for him," said Darryl Isherwood of Politicker NJ.
Gov. Chris Christie Had Weight Loss Surgery
The Republican governor is running for a second term in November, although his name is often mentioned as a possible presidential candidate.
Earlier this year, Christie was angered by comments from a former White House physician about his health. Dr. Connie Mariano was interviewed in a segment about the governor in which she talked about him having a heart attack or a stroke.
"It's almost like a time bomb waiting to happen unless he addresses those issues before he runs for office," Mariano told CNN.
The governor dismissed the critique, calling her "just another hack who wants five minutes on TV" and said Mariano should "shut up.''
Approximately 160,000 stomach-reducing procedures of various types are performed each year. Gastric bypass, sometimes called stomach stapling, is the most common, where surgeons shrink the stomach's size and reroute food to the small intestine.
Gastric band surgery, best known by the brand name Lap-Band, is a less invasive and reversible alternative, where an adjustable ring is placed over the top of the stomach and tightened to restrict how much food can enter.
The band creates a small pouch so that it only takes a small portion of food to make the patient feel full. The procedure is done laparoscopically using five small incisions, CBS 2's Dr. Max Gomez reported.
"Severe obesity is a life-threatening condition and the only effective treatment for morbid obesity is surgery," bariatric surgeon Dr. James McGinty told Gomez.
Candidates for gastric banding must have a body mass index of between 30 and 40 plus a weight-related medical condition, such as diabetes or high blood pressure, or a BMI of 40 and higher. They also must have previously attempted to lose weight through diet and exercise.
"With the proper diet and exercise, this tool will be very effective in helping him to lose a significant amount of weight and keep that weight off over the long term," McGinty said.
Christie's procedure was performed by Dr. George Fielding, head of NYU Medical Center's Weight Management Program, who did the same procedure for New York Jets coach Rex Ryan three years ago.
Fielding lost over 100 pounds himself following his own Lap-Band procedure.
He told Dr. Max Gomez three years ago how hard it can be to be morbidly obese.
"Deep inside every fat person is someone who just wants to be normal and a normal member of the community where no one gives them a second look," Fielding told Gomez.
Patients generally have to be more than 100 pounds over their ideal weight to be a candidate for lap-band surgery, Gomez reported.
Dr. Michael Bilof, bariatric surgeon at St. Barnabas Medical Center in New Jersey, said the surgery can certainly extend the governor's life.
"This surgery as I like to tell my patients its' about your health. It's about treating your medical problems you have or medical problems you would get given that you're obese," Bilof said.
The adjustable Lap-Band has been available in the U.S. since 2001 for the most obese patients. In 2011, the Food and Drug Administration expanded approval to somewhat less obese patients.
Christie said the cost of the surgery was covered by his insurance.
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