Kim Kardashian West is working to get her tummy ''back to flat'' after overindulging during the holidays.

The 'Keeping Up With The Kardashians' star - who has built a brand out of her curvaceous figure - revealed she has been taking part in a milkshake meal replacement diet since the start of the new year in a bid to get back in shape.

Kim, 37, shared a photograph on Instagram drinking milkshake in the kitchen wearing a tiny white crop top and skimp panties - showing off her impressive abs.

Kim told her 106 million followers: ''Little update for you guys. I'm on Day 9 of my Shake It Baby program from @flattummyco and I'm actually feeling so good.

''We had a massive Christmas this year and between my Mom's party, Christmas and New Years... I felt like it was impossible to fit in my regular work outs and eat healthy. But this program is giving me a kick in the right direction that I need. These meal replacement shakes are so good and it's helping me get my tummy back to flat in the new year. The results I'm seeing and feeling are amazing and I'm so excited for the next few weeks. Because they're all about getting women back on track ... (sic)''

But the reality star isn't being too strict about her diet it seems. Just one day earlier she shared a snap of herself getting ice cream from fastfood chain McDonald's and confessed: ''I'm craving McDonalds'.''

Kim and husband Kanye West are expecting their third child through a surrogate, with the arrival thought to be later this month.

Over Christmas their two-year-old son Saint was treated in hospital with pneumonia.

Kim - who is also mother to four-your-old daughter North - took to Twitter to defend herself after one fan queried why she was out partying for New Year's Eve (31.12.17) when Saint was ill.

Kim hit back: ''I haven't heard this BUT lets get this straight. I did not leave my son for one minute during his hospital stay. We were there Wednesday night to Saturday. NYE WAS SUNDAY NIGHT. People came over when he was already asleep for the night! Don't even try me when it comes to my kids (sic)''

She had previously confirmed her son was ''all better'' after being treated for the illness, in which a person's lungs become inflamed.

Kim tweeted: ''My precious baby boy is so strong! After spending three nights in the hospital & seeing my baby get multiple IV's and hooked up to oxygen machines, our end of year was challenging. Pneumonia is so scary. I just want to thanks every nurse & doctor out there who works so hard around the clock. We are so grateful for you all! He's home and all better. He's so resilient I'm sure he will still say the ambulance ride was cool! My strong Saint (sic)''