Knowles regained her pre-pregnancy figure in record time after giving birth to her daughter Blue Ivy in January 2012.
Kim, who recently welcomed daughter North with boyfriend Kanye West, hopes to follow in Beyonce's footsteps.
"She won't leave the house until she's thinner, she can't lose the weight fast enough. And she's frustrated she can't exercise yet,” contactmusic.com quoted a source as saying.
"She really looks up to Beyonce,” the source added.