Rob Kardashian shared an unusual throwback photo on Instagram.

The 28-year-old reality star returned to the social media site on Thursday by posting a shirtless picture of himself eating a pulled pork sandwich. "#tbt Me just chill-zoning in Malibu eating a pulled pork sandwich," he captioned the snapshot.

Kardashian largely keeps out of the spotlight, and rarely shares photos or updates.

The reality star's sister, Khloe Kardashian, admitted her brother is "not at his happiest place" in March, and confirmed he is still living with her in her recent Complex interview.

Kardashian has struggled with his weight in recent years, and simply declared, "Yes I'm fat now," on Instagram in February.

Mom Kris Jenner denied reports her son had entered rehab for substance abuse issues at the end of May.

Kardashian and his family came to fame on E! series "Keeping Up with the Kardashians," which will return from mid-season break in the fall.

Khloe Kardashian signed papers to finalize her divorce to Lamar Odom this month, but recently confessed to missing her husband "every day."