WASHINGTON (AFP) – Two Republican heavyweights came to the defense of First Lady Michelle Obama Sunday, breaking ranks with some of their party's top stars who have taken jabs at her campaign against obesity.

Mike Huckabee, a formerly overweight talk show host who is a possible presidential contender, took issue with conservative critics who say the first lady is unduly involving the government in personal and family decision making.

The critics include Sarah Palin, Minnesota lawmaker and Tea Party champion Michele Bachmann, and radio commentator Rush Limbaugh.

"I didn't say they're all wrong," Huckabee said on Fox News. "I'm just simply saying that what Michelle Obama is proposing is not that the government tells you that you can't eat dessert."

"What Michelle Obama has proposed is that we recognize that we have a serious obesity crisis, which we do," said Huckabee, who calls himself a "recovering foodaholic" who once weighed 135k (300 lbs).

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The former Arkansas governor pointed out that 75 percent of military age youths in the United States do not qualify for military service "because they're either overweight or obese and can't meet the minimum army standards."

"That's serious," he said. "This is no longer just a health issue, an economic issue. It is becoming an issue of national security."

New Jersey Governor Chris Christie, who has called himself portly, also distanced himself from conservatives critical of the first lady's efforts to encourage young Americans to stay fit and eat healthy foods.

"I think it's a really good goal to encourage kids to eat better," Christie stressed.

"I've struggled with my weight for 30 years. And it's a struggle. And if a kid can avoid that in his adult years or her adult years, more power to them. And I think the first lady is speaking out well," he added.

While "I don't want the government deciding what you can and what you can't eat. ... I think Mrs. Obama being out there encouraging people in a positive way to eat well and to exercise and to be healthy, I don't have a problem with that," Christie added.

Childhood obesity in the United States has tripled in 30 years.

Today, one in three US children are overweight or obese, meaning they are more likely than their normal-weight peers to grow up to be obese adults at higher risk of diabetes, cardiovascular disease and fatty liver disease.