Serena Williams showed off her slim figure in a bold swimsuit after revealing she’s been using a weight-loss medication. The athlete, 43, sported a bright yellow one-piece as she posed for a series of snaps Thursday. “melanin mellow-yellow ,” she captioned the Instagram carousel — and fans were quick to hype her up in the comments.

Slimmed-down Serena Williams launched her partnership with skinny jab brand Ro on Thursday, after revealing she used their weight loss medication to drop a whopping 31lbs.

Williams is adamant that the medication route - she won't say which brand she is taking - wasn't easy, and certainly not a shortcut to her losing 31lb (14kg) over the past eight months.