Margaret Qualley admits she was ‘wasted’ on tequila and weed while filming sexualised workout scene in The Substance – after clashing with director over her body shape

Margaret Qualley says a combination of intense physical training, alcohol and marijuana helped her navigate the most challenging scene of her career.

The actress, the daughter of Four Weddings And A Funeral star Andie MacDowell, plays provocative TV aerobics instructor Sue in the critically acclaimed film The Substance, opposite co-stars Demi Moore and Dennis Quaid.

But one pivotal scene, in which a Lycra-clad Sue gave a highly sexualized dance lesson, resulted in Qualley “crying in the bathroom” before she’d even finished filming her first take.

“That particular kind of sexuality doesn’t lend itself to me,” the 29-year-old actress said The Sunday newspaperShe admitted that she performed her choreographies in secret and that when the cameras finally rolled, she had to use a mix of tequila and weed to get herself through it.

“I was already drunk early in the morning because I thought, I can’t do this for everyone,” she added.

The actress, daughter of Four Weddings And A Funeral star Andie MacDowell, plays the provocative TV aerobics instructor Sue in the critically acclaimed film The Substance (pictured)

Described as a “body horror,” The Substance stars Hollywood legend Moore, 61, as a fitness queen who uses a mysterious black market drug to create a younger, sexier version of herself — played by Qualley.

However, Qualley admits that she initially had conflicts with director Coralie Fargeat, who also wrote the film’s screenplay, over her character’s physical presentation.

Personal trainers were hired to help the actress achieve Sue’s athletic body, but Fargeat – whose “vision of Sue was inspired by the Eighties, with a butt and boobs, think Jessica Rabbit” – was unhappy with the results.

“So I had to be like, OK, I did what you said and you’re not happy, so I’m going to take matters into my own hands,” Qualley explained.

Of Sue’s well-endowed appearance, she said: ‘Unfortunately, there’s no magic boob potion, so we had to glue it on.

“Coralie found an incredible prosthetics team that gave me the stretch of a lifetime, but not my life.”

The Substance received rave reviews and a 13-minute standing ovation at the Cannes Film Festival.

For this role, Moore had to be completely nude in a scene where Qualley’s character is “born.” In this scene, the older actress examines her own naked body before Qualley emerges and looks full-frontally at her own skin.

Qualley stars opposite Hollywood veteran Demi Moore, who plays an over-the-hill fitness queen who uses a mysterious black market drug to create a younger, sexier version of herself

Speaking at the Cannes Film Festival in May, Moore said the full-frontal nudity scenes in The Substance (pictured) were easier to perform with Qualley because she felt “safe” with her.

For this role, Moore had to be nude in a scene where Qualley’s character is “born”

Speaking at the Cannes Film Festival in May, Moore said the full-frontal nudity scenes in The Substance were easier to perform with Qualley because she felt “very safe” with her.

“I had someone who was a great partner, who I felt very safe with,” she said. “We were obviously very close — naked — and we also got a lot of levity in those moments about how absurd those particular situations were.

‘But ultimately it’s all about really getting the communication and mutual trust right.’

The Substance will be released in the UK and US on September 20.