Gwyneth Paltrow is 40 and fit!

The actress put her bikini bod on display yesterday -- slipping into a snakeskin two-piece while hanging out with designer Stella McCartney.

Posing without any makeup on her face, Stella snapped a pic of Paltrow wearing a bathing suit she designed and posted it onto her Instagram account.

"Sexy lady in Stella swimwear! Summer never stop! x Stella," McCartney wrote along with the pic -- which shows a very happy Gwyneth jumping through the air.

Anyone who saw "Iron Man 3" knows Paltrow is in killer shape these days, as her abs were heavily featured in the flick -- and she's also looking pretty great without makeup on, right?

See how her bod stacks up against other celebrity beach physiques in the gallery above!

Hot Videos