Christie made the remark in response to a child's question during a campaign stop in Council Bluffs, Iowa.
"What are you going to do about the lunches, because they were fine when Mrs. Bush was the first lady, but now that Mrs. Obama is the first lady, they've gone down," the child told Christie.
Christie, a Republican presidential hopeful, responded curtly by saying Obama should not be involved with changing school lunches.
"The first lady has no business being involved in this," Christie said to applause. "She wants to give her opinions? That's fine. She can give her opinions about what people should have for breakfast, lunch, or dinner. She's like any other American. She can give her opinions."
"But using the government to mandate her point of view on what people should be eating everyday is none of her business," he added.
In 2012, Obama partnered with Agriculture Secretary Tom Vilsack
to unveil new school lunch standards that require meals to offer fruits and vegetables to students every day.
The program, which at the time fed 32 million students in private and public schools, requires meals to also have reduced sodium, saturated fat and trans fats. The initiative is part of Obama's "Let's Move!" campaign, which began
as a response to childhood obesity doubling over the past 30 years.
Christie has struggled with weight himself, and Republican sources told CNN in 2014 that Christie had lost 85 pounds
In 2013, during an NBC News interview, Obama praised
Christie, tying his struggle with his weight with her White House campaign. She was asked to comment on Christie's lap-band surgery
"I think Governor Christie is terrific. His family is wonderful, and I wish them the best," she said. "The one thing that I will say is that there are millions of people like the governor who struggle with adulthood obesity, and that's one of the reasons why I think 'Let's Move' is so important, because we want to start working with kids when they're young so that they don't have these challenges when they get older."