Little Mix's Jesy Nelson upstaged the birthday girl last night as she showed off her weight loss in a revealing dress at Leigh-Anne Pinnock's party.

The 21-year-old was joined by the rest of her bandmates, Jade Thirwell and Perrie Edwards, as they celebrated Leigh-Anne's 20th birthday in London last night, but she certainly made sure to stand out from the rest of the girls.

The foursome headed to the Madison Restaurant where they partied with this year's X Factor hopefuls, their mentor Tulisa Contostavlos and The Only Way Is Essex star Lauren Goodger.

Jesy looked incredible in her silver shimmery gown, showing off her cleavage in a low-cut neckline while flaunting her toned abs in the cut-out around her midriff and her toned legs with a sexy side-split.

The 'Wings' singer's new look is miles away from the curvier girl who won The X Factor last year, and spoke of the cruel taunts she received on social networking sites for her figure.

We think Jesy looked great before, but she looks even better now! Check out the pics of Jesy and the rest of the girls enjoying the celebrations below...

Little Mix's Jesy Nelson Flaunts Weight Loss At Leigh-Anne's Birthday...