Kim Kardashian reveals 20-pound weight gain

Kim Kardashian can't stop tweeting about her alleged weight gain.

The newlywed and mother-of-one revealed via Twitter on Tuesday morning that she's packed on a few pounds since marriage and motherhood.

"Off to an intense workout. Can't seem to shake this last 15-20 lbs. of baby weight. No more excuses. my baby is 1 years old! UGH," the 33-year-old wrote. "I'm not gonna call it baby weight bc that's an excuse. I just gained weight & that's it. Why is it so much harder to lose after baby though?!!"

This news may come as a shock to those that saw the "Keeping Up with Kardashians" star on "Jimmy Kimmel Live" Monday night. Looking as svelte as ever, Kim donned a form-fitting outfit for her appearance on the late-night show, and made no mention of her weight gain.

RELATED: Who Was Hungover at Kimye's Wedding?!

"Do any of u moms see their bodies just not the same? a different shape?" the tweets continued. "Ughhhh my hips and butt are huge now! They were big to begin with!"

And then some more tweets...

"Just need to get down to my weight a few years ago. Not gonna complain anymore. Starting diet TODAY! No carbs. crazy workouts. Who's with me?" Kim writes. "I think after having a baby u get so excited u lost a lot of weight then u get comfortable and eat how you used and it creeps back up."

RELATED PICS: Kim's Sexiest Selfies

Finally, the reality star concludes: "OK no more tweeting and procrastinating! LOL Glad some of u moms can relate. I'm reading the comments! For real....of to the gym! ...Wish me luck on the dieting...it's soooo hard for me!"