Lean & Mean ‘Teen Mom 2’ Star Chelsea Houska Building Muscles With Crossfit: ‘She’s Making Progress And Won’t Stop Anytime Soon!’

Chelsea Houska just keeps getting fitter and thinner — and RadarOnline.com has the exclusive details about her brand new workout regimen!

As RadarOnline.com previously reported, the Teen Mom 2 star shed the pounds by taking kickboxing classes at Kosama Fitness Center this spring in her native Sioux Falls, South Dakota.

But earlier his summer, the MTV sweetheart was bitten by the crossfit bug.

“Chelsea goes to the Metabolic Fitness Center four to five times a week,” a friend tells RadarOnline.com of the Tea, South Dakota gym. “It involves heavy weights and cardio, so it’s definitely more effective. And she loves it!”

It looks like all the hard work has paid off. On July 26, the 22-year-old posted a sexy photo of herself wearing tight leather pants on Instagram.

http://instagram.com/p/q8LWdXna_S/?modal=true

And last month, she debuted her amazing bikini body in a mirror selfie.

While Houska’s beyond busy being a hands-on single mother to daughter Aubree, 4, and working full-time as a cosmetologist, she refuses to slack on workout time.

“It’s important for her to take time to work on her health,” the source says. “And she brings Aubree to the gym with her.”

Though Houska has clearly lost weight, the insider swears the star isn’t focused on numbers on the scale.

“She used to want to be skinnier, but now she wants muscles,” the friend explains. “She’s not where she wants to be yet, but she’s making progress and won’t be stopping anytime soon!”