The 30-year-old reality star, who wed NBA player Kris Humphries last month, went to the gym twice a day in the run-up to her big day.
But she revealed that she hasn't worked out since getting back from her honeymoon in Italy.
She tweeted on Saturday: 'OK, I need to get back on track with my workouts.
'I haven't worked out since I was in LA weeks ago. This is not OK! Gonna start tomorrow.'
And the Keeping Up With The Kardashians star appears to have stuck to her word, writing today: 'Didn't sleep so well last night.
'Woke up at 4am [with] weird dreams, a nightmare. So I went to the gym! Feel better that I started workouts again.'