Mandisa Hundley has struggled with weight issues most of her life. That didn't stop her from singing or from auditioning for the fifth season of "American Idol," which is currently being revisited on "American Idol Rewind," but it did give her pause when Simon Cowell joked that the show would need a "bigger stage" to accommodate her.

Now 80 pounds thinner, Mandisa tells ET she couldn't believe it when "American Idol Rewind" used that moment in the premiere episode of its new season, because, in the past, that was her worst nightmare come true. But she is past it now and she tells ET why, and about her weight loss and childhood abuse.

ET: For "American Idol Rewind," what was it like to relive that time of your life?

Mandisa: Amazing. I was watching the premiere episode and it was really neat to look back and see everything that has changed since then, because everything has changed since then! To be honest, the reaction that I have when I watch it back is I am so thankful, because I know that so much of where I am today has to do with my time on "American Idol." I look back with gratitude.

ET: You did new interviews for the new season of "American Idol Rewind." Did you have a favorite memory?

Mandisa: My favorite memory started out as my least favorite memory and that was when Simon Cowell made fun of my weight on the very first show. Of all the shows to be the premiere episode, so everybody was watching. That was my worst nightmare come true. It turned into my favorite memory of the entire show because when I saw Simon the next time, I told him I forgave him because an important part of my faith is forgiving others because I have been forgiven. I will never forget that reaction: the look on his face -- humbled and giving me a big hug. I have never seen him like that before. That is why I say I am grateful even for the difficult things that happened because they turned out working out for my good.

ET: Did you get together with any of your season's contestants, or did you do the interviews on your own?

Mandisa: We each did it on our own, but I did my interview in Nashville, which is where I live, so when I was coming out of my interview, Kellie Pickler was coming in for hers. It was really great to catch up with her on everything that has been going on in our lives.

ET: Talk a little about your latest album Freedom. I read somewhere that it is about overcoming your addiction to food? Is that correct?

Mandisa: Absolutely. That was kind of a theme. We didn't set out to make it that way, but it is another benefit from having my weight struggle be so public from the beginning of "American Idol." My first album was called True Beauty, and that was just me saying that my beauty is not defined by the way I look, and I still believe that. On Freedom, the songs were proclaiming things like I was set free. I thought, "How can I tell people that God has set them free when I am still bound?" It has been a life-long food addiction. When I was recording that album, I started to do the work necessary to be set free: changing my eating habits. No particular diet, just eating healthy. I started working with a personal trainer and a counselor who specializes in eating disorders. I have lost 80 pounds since I started recording it and since I have been singing those songs, so I have been set free finally.

ET: Losing 80 pounds is fabulous. Was there an inciting incident that started you on the path?

Mandisa: It was the combination of me being in the recording studio and singing, "My Deliverer Has Set Me Free," my first single, and I had a show in South Dakota and I went to Mt. Rushmore. In my mind, I am recording this song that says I have been set free, and while I am thinking about that, I am walking up this incline to see Mt. Rushmore and it was so hard. I was breathing heavy. I was sweating and my legs hurt. I realized, I had not been set free. I couldn't stand on the stage and tell people they could be set free, too. When I got home from Mt. Rushmore, I hired my personal trainer and that is when we developed an eating plan that I could live with the rest of my life, not a quick fix. I also started working with my counselor.

ET: Tell us a few specifics about the diet?

Mandisa: I don't believe in diets, because I have lost weight on them all, but the thing about diets is that you have the mindset that you stop a diet when you are done losing weight. This really is a lifestyle change for me. I did things like lean meats, mainly chicken and fish. Occasionally, beef, but I don't do a whole lot of pork. I try to focus the most on getting in my daily amount of fiber -- 20 to 25 grams, so I do a lot of whole grains, fruits and vegetables. I try to stay away from the processed foods, the white flours and sugar. High blood pressure runs in my family, so I try to limit my salt intake.

I couple that with resisting temptation and for me that is when my faith really comes into play. When I am tempted by the Krispy Kremes and the fast food, I have scriptures with me. I turn to those scriptures and they help me to resist temptation. One temptation at a time adds up. That is how I have been able to conquer it: one day at a time.

ET: Exercise?

Mandisa: I have a personal trainer, and we work out three to four times a week. We do some cardio, but we mainly focus on weight training so that I can be toned. I also do Zumba, which is my favorite form of exercise because it is dancing -- a Latin/hip hop dance party. I also add some cardio on my own. I usually exercise five to six times a week. I have videos on my Web site, mandisaofficial.com, following me on my journey to a 100-pound weight loss. The fourth video is all about Zumba.

ET: Did I hear that you were engaged? I always remembered that you were joking that you were interested in Ruben, but then I thought I heard you had gotten engaged?

Mandisa: No, you didn't hear that. Maybe they got me confused with LaKisha Jones from season six. She recently got married.

ET: Was it hard to publicly state that you had been abused and that part of the reason for your weight was that you felt that being beautiful was dangerous?

Mandisa: It wasn't hard for me. I recognized that it happens to so many women. One in three women is abused. Because I knew that I wasn't alone in that, and because I had come to terms with the fact that it wasn't my fault, I was a child. I was molested as a child and then raped when I was 16. Because there was no guilt and no condemnation, I felt it was an obligation to talk about where the root of my issues came from. There are so many women who struggle with that as well. I wanted them to know they aren't alone in that. There is healing that can be found after something like that happens.

"American Idol Rewind" airs in syndication and on the TV Guide Network. Check your local listings for the day and time in your city.