The 32-year-old reality star - who topped the scales at 240lbs in 2013 - has been struggling to slim down his bulky 6ft1in frame for the last seven years.
Kardashian - who was diagnosed with type 2 diabetes during a 2015 hospitalization - began his latest fitness journey on June 17, but it's unclear if family trainers Don Brooks and Gunnar Peterson are involved.
'Rob is doing great, he really is,' his big sister Khloé reassured earlier this month.
'You know, he's been working out...He goes to Kim's. He's worked out for like the past five days or so and he's kicking a** and I just want Rob to do what's best for him and what makes him happy, and if that makes him happy, then we will all support him.'
It's nice to hear that 38-year-old Kim was encouraging, having called her little brother the 'king of excuses' in 2015 and a 'jobless loser' in 2011 on their E! series.
It's hard to believe the USC Business grad and his partner Cheryl Burke managed to score second place in the 13th season of ABC competition Dancing with the Stars just eight years earlier.
One major reason Rob is trying to get healthier is for the sake of his beloved two-year-old daughter Dream with ex-fiancée Blac Chyna, whom he only dated for 11 months on/off.
When Kardashian isn't doting on Dream, he's been using his 9.8M social media following to promote his new skateboard clothing company Halfway Dead, which launched May 31.
Rob also keeps busy running the sock company Arthur George with his momager/roommate Kris Jenner, who holds 'a 50 per cent stake in the company' - according to The Blast.
