Rob Kardashian is ready for a change.

Kim Kardashian's younger brother has reportedly vowed to hit the gym and slim down, after being attacked by social media users over his recent weight gain. People Magazine reported that the 27-year-old sock designer missed his sister's wedding to Kanye West last weekend after becoming to self- conscious about appearing in photos because of his weight.

Gunnar Peterson, Rob and Kim's trainer, told TMZ that Rob texted shortly after landing in Los Angeles, California, from Paris on Saturday. Rob reportedly told Peterson that "he felt too fat to pose for wedding photographs."

Peterson said Rob is reportedly ready to "hit the ground running" with a new fitness regime. He is said to be willing to work out every day until he reaches his goal, which was not reported.

"Rob is locked and loaded," Peterson told TMZ.

Peterson told TMZ that he will have "no mercy" on Rob and has already planned to put him through an hour of "high-intensity full body exercises, cardio and resistance training." Rob reportedly visited the gym a few times before flying to Europe.

Several reports claimed that Rob skipped his sister's wedding after an argument with the family over his size. The sole male sibling of the Kardashian clan has reportedly been absent from the spotlight due to recent weight gain.

A source told the Daily Mail that Rob gained nearly 100 pounds and has been depressed for several months. Since being photographed in in Paris, Rob has stayed off social media and has deleted all his tweets before the wedding.