Brandi Mallory's Extreme Weight Loss family is in mourning.

In the wake of the season four star's death, her fellow contestant Kim Williams Maxile penned a heartbreaking tribute and reflected on how their friendship was forged.

"I'll never forget while I was at boot camp for season 5 we watched your season and it inspired us to keep going," she recalled in a Nov. 9 Instagram post. "Your episode was my favorite because we had so much in common from pageants to being a makeup artist and just a love of life. When my episode aired a year later you reached out and even though we never met in person (at that moment) you and I became sisters as only a small group of us know what life was like on the show and life after the show."

Upon their first meeting, Kim remembered that "it was like we've known each other our whole life" and the two immediately formed a strong bond.

"We laughed we cried, we created a project together and I knew we'd be sisters for life," she continued. "You truly made an impact on this world with your zest and your passion for body positivity. I'm blessed to have gotten to experienced you in this world. Love you so much sis."

Brandi died on Nov. 9 in Stone Mountain, Ga., according to her obituary. She was 40.

A cause of death has not been revealed. 

Brandi appeared on the fourth season on the ABC show in 2014, losing a total of 151 lbs. over the course of a year. At the time, she credited her weight loss to exercise and eliminating meat from her diet.

"After taking on this year, and believing in myself in a way that I never did before, I believe I've reached the point where I no longer care what others think of me," she told the Atlanta Journal-Constitution after her episode aired. "What matters most is what I think and, of course, what God thinks of me."

As for what motivated her to turn to a healthier lifestyle? Brandi—who initially auditioned for The Biggest Loser—said a fatal heart attack that took the life of a sorority sister in 2012 was the catalyst for change.

"That scared me," she told the outlet. "When my sorority sister passed, I started to live in fear about when my time would come."

Amid news of Brandi's passing, her sorority sister, fitness coach Jasmin Murphy, took to social media to pay her respects and described the Georgia native as a "remarkable individual whose life and legacy touched so many."

"I am deeply honored to have been able to call you a friend," she wrote. "Brandi was a shining light in the plus size beauty and fitness industry, a beacon of positivity, transformation, and genuine human connection. Brandi's passing leaves a void in our hearts, but her spirit, teachings, and the memories we shared will continue to inspire and guide us."