Jordin Sparks revealed one of her biggest weight loss secrets in an Instagram photo: her boyfriend Jason Derulo! Jordin Sparks calls him the "best workout buddy," and reveals to fans how her boyfriend encourages her to exercise and stay fit.

In an Instagram photo posted last week, Jordin Sparks revealed one of her weight loss secrets of 2014: Jason Derulo.

"You know what? @jasonderulo is the best workout buddy! Thanks for encouraging me & pushing me to go harder!! BOOM! #getitrightgetittight #healthie #speezyfitness," Jordin captioned the photo, which features the "One Wing" singer and her boyfriend sweaty and in fitness clothes, sitting on an exercise mat.

Jordin Sparks lost 50 pounds in a little over a year! She previously posted another Instagram photo about staying motivated to get fit.

"When you push through not wanting to go, that's when you see results. #speezyfitness #healthie #getitrightgetittight," Jordin Sparks captioned the Instagram photo below.

Her toned legs are on full display in her tight black leggings as she takes a selfie in the gym.

As we previously reported, Jordin Sparks, 24, told Today's Jenna Bush Hager that her weight loss efforts were successful because she made her health a priority, E! News reports.

"I was comfortable with how I looked before, but it was about really focusing on become healthier," Jordin Sparks said. "And then my body changed, which was awesome. But it wasn't about being a size zero, or anything like that."

"I fluctuate a bit. I go anywhere from 155 to 161," she said. "There we go! There it is in a box, in a nutshell, right from my mouth. That it is how much I weigh, and I'm okay with it. It feels really good," the 6-foot beauty said with a smile.

Jordin and Jason were also recently featured in a fall photoshoot for Us Weekly magazine. The spread, called "Buys for Your Guy," focuses on presents and style choices for your significant other, based off of the fall trends Jordin Sparks picked for boyfriend Jason Derulo. Check it out in the latest copy of the magazine!