Rob Kardashian Posts Throwback Picture, Suggests Milkshakes Kicked Off His Weight Gain

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Started from the milkshake now we're here.

♫ My milkshake brings all the boys to the yard ♫

After snapping a picture of his recent workout, Rob Kardashian posted a new throwback picture on Thursday, seeming to reference his changing appearance over the last two years, writing, "Started right here with these milkshakes hahaha?? ??... #throwbackthursday."

WATCH: Rob Kardashian Steps Out for Workout, Runs Into Kylie Jenner and Tyga

The 28-year-old Kardashian appears to be focusing on fitness right now! Earlier this week, he posted a picture from his run-in with Kylie Jenner and Tyga on his morning workout, writing, "Spotted these fools on the morning workout."

Kim Kardashian has tweeted about a couple workout sessions with Rob, on Tuesday writing, "Rise & Grind! Workout time!!!!! With @robkardashian."

Earlier in August, she tweeted, "Just went on the hardest hike ever today with @robkardashian."

WATCH: Rob Kardashian Steps Out for First Time in Months: See the Pics!

Meanwhile, Rob's not the only one putting up his throwback Instagrams! A month ago, Kendall Jenner posted this throwback video of Rob laughing, writing, "This makes me ridiculously happy."

WATCH: Kris Jenner Worries Rob Kardashian Is 'Going to Die,' Says He's Gained 100 Pounds In the Last Year

Right now, Rob is getting things together in his life, and living with his sister, Khloe, which she is loving, by the way.

"Rob lives with me now and I wouldn't have it any other way. I love having him with me," the 31-year-old reality star told Complex magazine. "He's going through a hard time now and it's behind gates. With this crazy lifestyle you have to think of places where you can still have your freedom."

You go, Rob!