David Walliams calls Simon Cowell a 'skinny b***h' in hilarious tweet as the music mogul shows off his toned torso after year-long vegan diet

David Walliams has poked fun at his friend Simon Cowell's slimmed-down physique by calling him a 'skinny b***h' in a hilarious Twitter post. 

The former Little Britain star, 48, shared a shirtless snap of his fellow Britain's Got Talent judge, 60, during his annual Christmas holiday to Barbados. 

Simon has lost a considerable amount of weight in recent months thanks to a strict vegan diet and it seems he has impressed David with his dedication to healthy living.

It comes after David recently posted another snap of himself alongside Robbie Williams where the singer left little to the imagination by posing in his underwear.

Posing in a black printed t-shirt and matching bottoms, Robbie stood alongside a fully-clothed David who wrote: 'He looked different online...'  

Simon's new physique comes after he ditched his old diet in favour of a vegan lifestyle after advice from a doctor. 

The music manager showed off the fruits of his labour, his newly taut stomach on display, as he headed to the ocean with his five-year-old son Eric for a splash in the crystalline waters on Wednesday. 

Simon - who whisks his partner Lauren Silverman, 42, and their son off to the same resort at Christmastime every year - looked great as he walked along the sand in inky grey shorts. 

Showcasing his trim physique, the TV judge appeared more than happy to be on his vacation - having to leave a little later this year thanks to his series X Factor: The Band only finishing on Sunday.

Simon shed more than 20Ibs in weight thanks to a fastidious vegan diet, which he changed in order to keep up with young son Eric.

He told The Ellen DeGeneres Show: 'I went to see this doctor in London. We did some tests. And then a month later he said, "You have the worst diet I've ever met from any patient."

'So I went, "Okay, out of the smoking, the drinking, and diet, what do I have to drop?" And he said, "The diet." So I said, "I'm in!"

'It was easier than I thought, and part of the reason I did it was because of Eric. I realised if I didn't sort myself out physically, I wouldn't be able to catch up with him.

'Because the minute he gets up to the minute he goes to sleep... their energy, you forget, at five years old, is phenomenal.'

Simon previously said he'd named his diet the Eric Cowell diet after his son, because the youngster loves to munch on raw vegetables.

He said: 'It's like the Eric diet because he actually, apart from ice cream, he actually likes water. I mean, who likes water? And his raw vegetables. So I'm on like, the Eric Cowell diet.'

Earlier this year, the music mogul's Britain's Got Talent co-judge Amanda Holden credited a different reason behind Simon's weight loss, claiming it was his switch to 'skinny lager'.

Talking on Good Morning Britain to Piers Morgan, she said: 'He’s drinking lightweight beers, that’s the secret. And I tasted it because I thought it was gonna taste, like, naff. Actually it’s quite decent. You could take a tip from him!'

Simon also spoke about cutting down on alcohol earlier this year, he told Extra: 'I went to see this guy who’s very well-known. And he said to me, after doing some blood work, "You can’t have red meat, dairy, sugar, bread or gluten."

'I’m thinking, "What about alcohol?" And he said, "Maybe not quite as much as you had before." And I did it and I stuck to it and it’s easy.'