They must be the hardest working leggings in showbusiness.
Kim squeezed her famously curvy figure into a pair of Spandex workout pants as she headed to the gym on Tuesday.
While Kim's modest outfit was designed to be practical, it also revealed what is fast becoming her most talked about feature - her bottom.
The hardest working leggings in showbusiness: Kim Kardashian covers her behind in stretchy workout pants as she heads to the gym in Los Angeles on Tuesday
Early start: Kim began the day with a pilates class
The stretchy material clung valiantly to her famously plump posterior, which the reality star has furiously denied was enhanced by implants.
Kim teamed the leggings with a simple workout outfit of a T-shirt, zipped sweater and scarf as she braved the early morning chill.
Arriving for her pilates class in Los Angeles, she hid her make-up free face beneath sunglasses, and tied her hair back.
Can't hide this! Kim revealed the full expanse of her beach bum on holiday in Thailand last week
The 33-year-old is back to her normal routine after taking a break for a family trip to Thailand.
While there Kim revealed her behind in all it's curvy glory in a series of tiny bikinis.
One shot caught her posing on the edge of a red sailboat.
Bottom perched on the side, and powdered with sand, Kim made sure to show it off to best advantage.