The 38-year-old supermodel decided to undergo a breast augmentation after she breastfed her kids - Benjamin, now, eight, and Vivian, now five - but immediately regretted her decision.
She told People magazine: "I was always praised for my body, and I felt like people had expectations from me that I couldn't deliver. I felt very vulnerable, because I can work out, I can eat healthy, but I can't change the fact that both of my kids enjoyed the left boob more than the right. All I wanted was for them to be even and for people to stop commenting on it. Things can be looking perfect on the outside, but you have no idea what's really going on."
And Gisele - who has her two kids with her husband Tom Brady - has praised the American football quarterback for supporting her through the ordeal, which took place secretly in 2015.
In her memoir, 'Lessons: My Path to a Meaningful Life', she admitted: "When I woke up, I was like, 'What have I done?' I felt like I was living in a body I didn't recognise.
"For the first year I wore clothes because I felt uncomfortable. He just said, 'I love you no matter what' and that I looked beautiful.' This was definitely another lesson: What doesn't kill you makes you stronger. But I wish I would have learned that a different way."