At 356 pounds, 21-year-old Liana Sims knew that though her weight had yet to kill her physically, it had already been fatal to her confidence. She stopped traveling because airplane seatbelts couldn’t meet around her waist. She declined friends’ invitations to the local amusement park for fear that she wouldn’t fit on its rides.

“Will this chair collapse if I sit in it?” she asked herself. “What if I go to a restaurant and end up sitting in a booth? Will I fit? These are the experiences that conquered me. I was not living.”

Having battled obesity since the third grade, Sims learned early on how to minimize embarrassment. “I sat toward the front of the school bus so I didn’t have to make my way down the aisle,” she says, noting that she often sat in the front of her classrooms for the same reason. “Maneuvering between all of the chairs became uncomfortable.”

The self-professed food addict found solace in plates of food and nutritionally sparse choices. “Sometimes, I would just have a big bag of chips and a soda for lunch. I would literally think about food all day, and once I got my hands on a particular item, I just wanted that moment to last,” says Sims, now 27, and a youth pastor of the Fellowship Central Bible Church in Los Angeles. As a teenager, Sims frequented fast food restaurants and ordered two meals for herself. “I was an equal-opportunity eater. My flesh was insatiable.”

Sims was 16 when she recognized preaching as her calling, although she did not know how public speaking would manifest in her life. “I had a fear of being on a public platform even though I believed it was my passion. I was afraid of being made fun of.”

But yet, Sims– more than 100 pounds overweight and wearing a custom-made gown – was crowned high school prom queen in 2004. After being inspired by the 2001 film “The Princess Diaries” (in which a teenage outcast learns of her royal lineage and transforms into an attractive heiress), Sims gave into what she called “the craziest idea ever. What 300-plus pound girl goes out for prom queen? But I had this courage telling me to let who I was shine. [Winning prom queen] prompted me to stop thinking in terms of the impossible.”

Upon graduation, Sims enrolled at Biola University, a Christian college near her hometown of Inglewood, California.  As her peers faced packing on the proverbial freshman fifteen, Sims found a new means to indulge in her old habits. “There was an all-you-can-eat cafeteria, and I could easily drink three sodas in one sitting. [My friends and I] would be in the cafeteria for hours, kicking it, and the next thing you know, we went back for more food.”

Sims explored her passion for ministering to others by joining a campus mediation group, later making a commitment that would shift her lifestyle choices. “I told myself that I would never preach a gospel that I didn’t live. So I either had to stop preaching or start living. And if I wasn’t living, I needed to confront why.” All roads led to the insecurities surrounding her weight. “I realized I was captive to my weight, and the captivity was in my mind. I believed that I had gotten to the point of no return. I had no blueprint, but I believed that, like the scripture says, who the Son sets free is free indeed.”

In 2007, Sims decided to make small changes to her routines. The one-time soda guzzler drank only water and lost 20 pounds within one month. She also rode a bike on campus and walked to complete errands. “I also took a swimming class at school. I knew I’d be apt to perform if my grade was on the line,” says Sims, who lost an additional 20 pounds in the two months of increased physical activity and later joined a gym. She began making better decisions at the campus cafeteria. “I leaned toward the salad bar. I took one piece of bread off a burger. If I ate heavy foods, I ate them earlier in the day so I had time to burn them off.”

After dropping her first 100 pounds, Sims began documenting her weight loss journey on YouTube. The “Watch Queen Lose” series has garnered thousands of views, and features everything from Sims’ candid victories (“Little things that are huge in the world of the obese person, like crossing my legs and wrapping a towel around my body”) to video of the tummy tuck she underwent to rid her stomach of sagging extra skin.

“Maintenance is its own battle,” Sims says. Now 180 pounds, she remains committed to clean eating and exercising three to five times a week. She also knows when to counter her weaknesses. “If a bread basket is in front of me at a restaurant, I’ll eat the whole thing. For me, strength is telling the waiter, ‘Don’t bring out the basket.’”

Then there are some setbacks that are out of her control. When Liana’s father, Kamau Sims, unexpectedly passed away last year, she went weeks without working out, balancing trauma with her personal goals. She shared her trials on YouTube: “If my dad could see me living, how would he see me living? He saw me as an overcomer…And that’s who I am.”

The girl whose weight once kept her from the limelight has now been featured on The Today Show and the final season of The Oprah Winfrey Show. And last spring, Sims clipped an airplane seatbelt across her waist and frolicked through Europe on vacation, snapping shots of her hard-won physique and unafraid to put her adventures in the insta-spotlight, uploading photos to social media often with the caption, “Daddy, I hope you can see me LIVING!”