Khloe Kardashian is currently wearing swimsuits as underwear because her bum has become so big.

The 33-year-old reality star - who gave birth to her daughter, True Thompson, on April 12 - has discussed the challenge of regaining her pre-pregnancy figure on her Snapchat account.

The 'Revenge Body' star shared: ''Day two in the gym. My body is so sore today. I woke up hurting, but [it's] the best thing ever. Day two, let's see how this goes. I hope it's a little better than yesterday.''

Later, Khloe showed off her workout wear, revealing: ''My ass and thighs are so big now that I am now wearing my swimsuit on the bottom.

''So, I hope it sweats some of it off. Let's start with the cardio before Coach Joe gets here.''

Khloe previously admitted she's found it a ''struggle'' to get back into the ''groove of working out'' because her body isn't as strong as it was before the baby.

She explained: ''It is a struggle getting back into the groove of working out - mentally I'm strong but physically it's just not the same. My body is not doing what my mind wants it to do. So it's a struggle but it's only day one.''

The curvaceous star is also finding it tough trying to fit her workouts around her little girl - whom she has with her boyfriend Tristan Thompson - because she constantly wants to feed.

Khloe said: ''I need to motivate myself and it's also a struggle trying to fit in working out in between feeding. No two days are the same. True is so great but still I can't predict if she's going to sleep for the whole two hours or if she's hungry.''