Last February, Frederickson drew gasps and criticism after losing 155 pounds, which totaled 60 percent of her body weight, for the finale of the NBC show.
Nearly two months later, Frederickson said she's put on 20 pounds, which puts her weight at 125. She told the magazine she's at her perfect weight.
Initially critics said she went too far with her long workouts and strict diet, but she's relaxed her routine since then.
"I work out an hour, six days a week. I love classes like SoulCycle," she told the magazine. "I also loosely count calories, but sometimes I might eat an Oreo. It's not the end of the world."
Despite all the criticism and backlash, she told the magazine she doesn't regret anything about her weight loss journey. She said the negativity was "a gift" because "it started a discussion about body image. ... That's huge."
And, although she lives in Los Angeles, she doesn't forget her Minnesota roots.