In an interview with Women's Health for their April cover story, the 36-year-old talked about the three miscarriages she experienced within a span of less than two years before the birth of her second son, Jacob, 13 months. The "Cry Pretty" songstress also has another son, 5-year-old Isiah, with husband Mike Fisher.
"For my body to not be doing something it was 'supposed to do' was a tough pill to swallow," Underwood told Women's Health. "It reminded me I'm not in control of everything."
After opening up about her miscarriages, the "American Idol" alum felt a "weight lifted off my shoulders." Underwood's candor also inspired other women to come forward about similar experiences.
"It's not a dirty secret," she expressed. "It's something many women go through."
The Grammy winner also spoke about her struggle with body image over the years. According to Underwood, during her time on "American Idol" in 2005, trolls criticized her online and called her "fat."
"I shouldn't care what other people think about me," Underwood recalled, admitting that her diet of quesadillas and pasta wasn't healthy. "I was tired, and I kept buying bigger clothes. I knew I could be better for myself, and I let my haters be my motivators."
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When the "Before He Cheats" singer went on the "American Idol" tour following her win, she decided to make healthy changes like counting calories, reading nutrition labels and working out. "I was sleeping better, and I had more energy for our grueling schedule," she explained.
However, she then began to take her new lifestyle too far by exercising more and eating less. As Women's Health notes, at one point, Underwood was consuming as little as 800 calories a day -- and she struggled to stick to her strict diet.
"I would 'fall off the wagon,' then feel terrible and repeat the cycle," she recalled. "Your body is screaming out, 'I need more calories, I need more carbs!'"