“Women should have the freedom to do whatever they need to do to feel good about themselves,” the first lady told People magazine. “Right now, I don’t imagine that I would go that route, but I’ve also learned to never say never.”
Her message to women is to be healthy. Mrs Obama says she has never missed a health checkup, including mammograms and cervical smear tests. She’s also had a colonoscopy.
“I don’t obsess about what I eat, but I do make sure that I’m eating vegetables and fruit,” she added. “And as everyone knows, I do exercise.”
Her “Let’s Move” campaign to reduce childhood obesity rates through the combination of exercise and healthier eating enters its fifth year next month.
Her workouts have also evolved from weight-bearing and cardio exercises to include things like yoga that she says will help keep her flexible.
Asked whether she has peaked at 50, Mrs Obama joked that being first lady is “pretty high up”.
She said she’s always felt that her life is “ever-evolving” and she doesn’t have the right to “just sit on my talents or blessings”.
“I’ve got to keep figuring out ways to have an impact, whether as a mother or as a professional or as a mentor to other kids,” the first lady said.
She said that daughter Malia, now 15, will be in college when she and President Barack Obama leave the White House in January 2017. Other daughter Sasha, 12, won’t be far behind.
“At that point in life, whoa, the sky is the limit,” Mrs Obama said.
President Obama is planning a big birthday dance party for his wife at the White House on Saturday night. Aides are keeping a tight lid on details of the party to maintain the element of surprise for Mrs Obama. Guests have been told to come prepared to dance and to eat before they come.
“There’s one thing I can tell you for sure... people will move,” said Valerie Jarrett, a senior White House adviser who is close to the Obamas.
Jarrett wouldn’t comment on reports that Beyoncé, who also is close to the Obama family, will sing at the first lady’s 50th party.
Beyoncé serenaded the Obamas as they danced at one of the balls for the president’s first inauguration in 2009.
Last year, she famously lip-synched to a pre-recorded voice track of the national anthem at Obama’s second swearing-in ceremony at the Capitol.
Coincidentally, Beyoncé’s husband, rapper and entrepreneur Jay Z, brings his Magna Carter World Tour to Washington’s Verizon Centre tonight, two days before Mrs Obama’s White House birthday bash. That means Beyoncé could be in town anyway.
Like all first ladies, Michelle Obama’s every move and fashion choices have been closely watched — and mercilessly critiqued.
She gets wide credit for carefully shielding daughters Malia and Sasha from public glare and for a strong sense of style.
But there have been missteps, too, like wearing $500 (€360) sneakers to a food bank, taking a pricey vacation to Spain during the economic downturn and being photographed wearing shorts aboard Air Force One.
Still, more of the public views Michelle Obama favourably, 59%, than her husband, 46%, in an Associated Press-GfK poll conducted last month.
And she’s helped raise millions of dollars for him and other Democratic candidates and drawn thousands to campaign rallies.