This is something of a coup for the Trafalgar Studios, which, after a shaky start, has established itself as a hip and credible alternative to mid-size arts powerhouses like the Donmar and the Almeida. It’s not just the off-the-telly star cast (My Family’s Kris Marshall, Gavin and Stacey’s Joanna Page, Peep Show’s Robert Webb) — a new play written and directed by Neil LaBute is always an enticing project.

Those who came to LaBute through his darkly misanthropic plays The Mercy Seat and The Shape of Things, or his films In the Company of Men and Your Friends and Neighbours — all of which positively twitch with loathing for humanity — might be surprised to see his name attached to a comedy. But he is also the man who helmed the hilariously bittersweet Nurse Betty, and even the bleakest of his own works are scored through with caustic humour.

Although American reviewers found Fat Pig very funny, it turns out not to be all sweetness and light. It concerns the love affair between slender, good-looking Tom (Webb) and the smart, attractive but unmistakeably plus-sized Helen (Ella Smith), and the damage wrought upon it by Tom’s ex-girlfriend Jeannie (Page) — who takes his new relationship as a personal affront — and his body-fascist workmate Carter (Marshall), who is simply affronted by excess curves.

Wittily, but not always happily, the play explores the tyranny of standards of physical beauty, which was also the subject of The Shape of Things.

Since LaBute himself is not exactly as slender as a bluebell (the fact that he’s a big, beardy, happily married Mormon is often cited in ironic counterpoint to the gloominess of his work), it’s no surprise that he’s made the Juno-esque Helen sympathetic and, ahem, well-rounded.

But equally unsurprisingly, he gives the loathsome Carter the best lines. Anyone who fears that Kris Marshall, commonly cast as a nice guy, won’t be enough of a cold-hearted bastard here clearly never saw his convincing West End turn as Billie Piper’s abusive boyfriend in Treats last year.

Now previewing (0870 060 6632, www.theambassadors.com/ trafalgarstudios