Kim is famed for her fabulous curves and is reportedly having trouble adjusting to her pregnancy body.
'She's gone from a 36D to a 36G and is wearing sports bras daily. Kim loves her curves, but she's upset that nothing in her wardrobe fits her any more. Her appearance is what had made her career, but she's conscious she is gaining weight,' a source told British magazine Heat.
'She's stepping it up a notch. It's a time when most women would just want to let themselves go. Kim's first priority is her baby, but she's also committed to her career and a lot of that relies on the way she looks. It's tough and she's not enjoying it.'
Kim has been spotted at the gym more than ever over the past couple of weeks.
The reality TV star has stepped up her visits to five or six times a week and now includes extra cardio and Pilates in her thorough workouts.
'It feels like a losing battle to Kim, though, as she is going to gain additional weight no matter what,' the source added.
'Some people can stay thin when pregnant, but her body type seems predisposed to get bigger.'
Meanwhile, Kim has given pal Brittny Gastineau a tour of her extravagant wardrobe for Eye on Glam, showing off a pair of $90,000 sneakers.
'Ridiculous, right?' she admitted. 'They didn't [manufacture] a whole lot. Luckily I know someone, who was able to get me a pair.
'I have love affairs with so many shoes,' she added.
Kim, 32, also explained why she has so many items in her closets.
'I think I'm still finding my style. I try things all the time. Some things work, some things don't,' she revealed.