It's not the first time the Irishman has lauded his gains, Tweeting side-by-side snaps back in November.
The 31-year-old will face veteran Donald Cerrone in the welterweight division on January 19, his first fight since October 2018 when he was taken out by Khabib Nurmagomedov in a lightweight title bout.
The Irishman was banned for six months following a post-fight brawl but hasn't laid low in the meantime. McGregor was charged with assault in April 2019 after punching a man in an unprovoked attack at a Dublin bar.