Rebel Wilson showed off her weight loss transformation in an Instagram post. The "Pitch Perfect" star recently gushed on her Instagram account about dropping some pounds after only a few days.

On Monday, the actress who plays Fat Amy in the popular aca-movie, shared on her official social media account that she has dropped eight pounds in just four days. She also shared the secret behind the success.

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"OMG just finished 4 fantastic days at #TheRanch4.0...so challenging but very rewarding! Not to mention I lost 8 pounds from marathon hiking over the 4 days!" Wilson captioned her photo.

"Thanks to the amazing staff and masseuses (free daily massages are part of the program)!! Feeling great!! @theranchmalibu @fswestlake #TheRanch4.0 #theranchatliveoak," she concluded.

 OMG just finished 4 fantastic days at #TheRanch4.0 ...so challenging but very rewarding! Not to mention I lost 8 pounds from marathon hiking over the 4 days! Thanks to the amazing staff and masseuses (free daily massages are part of the program)!! Feeling great!! @theranchmalibu @fswestlake #TheRanch4.0 #theranchatliveoak

A photo posted by Rebel Wilson (@rebelwilson) on Apr 25, 2016 at 11:26am PDT

E! News did a research about The Ranch in Malibu that contributed to Rebel Wilson's weight loss. The news site found out that the wellness retreat is a go-to for Hollywood A-listers. Among the destination's clients are Jesse Metcalfe, Lea Michele, Minka Kelly, Mandy Moore, Busy Philipps, Angela Bassett and Selma Blair.

The R4.0 that Wilson availed off is the four day version of The Ranch's weeklong program. Its website said that this course, which is done from Thursday to Monday, targets those who wish to "jump-start to a healthier lifestyle."

The program includes eight hours of rigorous exercise with mountain hiking and stretching. There are also cooking demonstration and massages.

The stay requires $15,000 deposit, according to MSN. Aside from the physical part, guests are also required to commit to banning soy, alcohol, gluten, caffeine, processed sugars and dairy.

Rebel Wilson's weight loss came a few weeks after it was revealed that the "Pitch Perfect" star is set to play Ursula in a live concert featuring songs from "The Little Mermaid." She will be featured alongside Sara Bareilles who will play Ariel and "Glee" actor Darren Criss who is set to play Prince Eric.

TagsRebel Wilson, Rebel Wilson weight loss, Rebel Wilson Pitch Perfect