Los Angeles - Rob Kardashian has lost 50lbs (22.6kg).
The sock designer currently weighs 248.4lbs (112.6kg), down from his heaviest weight of 298lbs (135.7kg), but wants to lose another 50lbs before his fiancée Blac Chyna's birthday in May.
He wrote on Instagram: "Looking from where I started 298lbs to my current weight now 248.4lbs. I'm focused and determined to reach my goal weight 200-205lbs .... Happy I found my motivation."
And it is believed his motivation is his fiancée, who he recently proposed to after a whirlwind romance.
Last week Blac, 27, revealed she was planning to get Rob in shape by her 28th birthday on 11 May on Snapchat.
Watch the snaps here:
She has also shared numerous snaps of Rob working out towards his goal.
Watch the snaps here: