Today, Boyce never misses a workout and has become an avid runner, competing in races with the goal of completing her first marathon.
It may have to wait until after the Miss America competition, which takes place in Las Vegas on Jan. 14.
"Going to Miss America is a dream come true," said Boyce. "My older sister had always competed in pageants, and I was always in the background, the chubby little supportive sister. I always wanted to compete but didn't think I could because of my weight."
On her way to shedding pounds the healthy way, Boyce said someone suggested she enter her local pageant and make her weight loss journey her platform.
Boyce had lost 74 pounds by the time she won Miss Florence in 2009. The following year, she cracked the top 10 for Miss South Carolina. On July 2, she finally took the title, singing "Tu Tu Piccola Iddio" from the opera "Madame Butterfly."
Now she shares her weight-loss journey and tips for healthful living with schools and other groups. She started an "Eating Healthy and Fighting Obesity" Facebook page "to inspire all ages to become healthy through good eating habits, exercise, and believing in yourself."
The page is filled with well wishes from around the world. Boyce promises to respond to all the people who have sent her messages asking for help with their own weight loss jouney.
She says her message is very relevant in a country that has seen an obesity epidemic in young people. She's hoping to work with First Lady Michelle Obama, who has corresponded with her, on tackling the problem.
"A lot of people ask me if I would change the past," Boyce said. "Then, I wouldn't have this amazing story to tell people."