Nathalia Teixeira lost over 100 lbs. during her weight loss journey
Credit: Courtesy Nathalia Teixeira

Nathalia Teixeira always led an active life, until she got married and took a job that required her to be sitting at a desk most of the day.

“I was never overweight when I was growing up,” the mom-of-two, 29, tells PEOPLE. “I started gaining weight when I got married at 18 – my husband is an ‘indoor person.’ Then I got a desk job, and as I was adapting from one lifestyle to another, I was carelessly eating.”

The self-described “chocaholic” would buy a giant bag of chocolates, and eat the entire thing by herself over the course of a day.

“I didn’t do any activities except to eat and sit,” she says. “I did realize I was gaining weight, but I was always like, ‘I’m going to start Monday,’ but Monday never started.”

By 2012, the 5’5″ psychology student weighed 265 lbs. She knew she needed to make a change, so she decided to post a video blog on YouTube about her unhappiness and her decision to lose weight in order to hold herself accountable.

“If I exposed myself, I knew I wouldn’t turn back on my promise,” she explains.

Teixeira completely cut out junk food and her beloved chocolate from her diet, and met with a doctor who put her on an extreme low-calorie diet for six months. She lost a significant amount of weight, but was eating so little that she couldn’t work out.

“As I started losing the weight, I had an urge to do exercise,” she says. “So I stopped, and I decided I needed a challenge.”

Even though she had never run in her life, Teixeira decided to do a 13-mile Spartan race.

“It was horrible,” she admits. “Even though I had trained 9 months, I thought I was going to die. Then I plateaued because I didn’t know how to eat correctly.”

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Between her diet and training for the race, Teixeira had already lost 80 lbs., but wanted to lose more.

“I wasn’t happy with my body, and I knew if I lost 80 lbs. I could do more,” she says.

Teixeira decided to take up a new challenge – competitive bodybuilding.

“I wanted to see how far I could push myself,” she says. “I wanted to be able to walk up there and say, ‘I was obese and I did this.’ ”

While many people did not take her seriously at first, Teixeira found a trainer who took on the challenge of getting her competition-ready.

“The first five minutes of training was horrific,” she says. “I vomited and I cried. I got so angry and so embarrassed, I picked up my stuff and I left. But the next day I was there.”

Over the next year and a half, Teixeira worked out every single day, doing a combination of weight lifting, CrossFit and twice-daily cardio. Thanks to her hard work and dedication, she dropped down to 140 lbs. with 10 percent body fat, and was ready to compete in her first bodybuilding show in November 2014.

“I just wanted to step up there, I didn’t even want to win anything,” she says. “It’s not my dream to be a professional bodybuilder. I just did it the first time for the challenge, and then I enjoyed so much, I did it a second and third time.”

Teixeira has competed in three National Physique Committee competitions, and placed 3rd at her most recent one.

“For me it’s fun as a hobby because it keeps me motivated and gives me a goal to work for,” she says. “But it’s become a pleasure and a lifestyle to go to the gym. It doesn’t feel like an obligation any more. Now it’s part of my life.”