When the trailer for Disney’s Cinderella remake was released, people weren’t just talking about the excellent casting of Cate Blanchett as the evil stepmother.

• The Angelina effect: should you have your ovaries removed?
• Lily James defends Cinderella’s waistline
• Alan Rickman on getting a bit surprise from Kate Winslet

The film’s star, Lily James, was forced to defend herself against criticisms her waist appeared “too tiny”, claiming her appearance was the natural result of healthy eating and a corset.

The 25-year-old James, who is 170cm tall and naturally slim, cinched her mid-section down to a tiny 43cm, around half the size of the average Australian woman.

James on the red carpet this month (left) and as Cinderella.

As critics question whether body image has any place in a children’s fairytale, audiences react to another far different movie trailer.

In Southpaw, Jake Gyllenhaal plays a championship prizefighter. In the film’s previews, he appears alarmingly muscular, having gained 6.8kg of muscle for the role.

Even more alarming is the fact Southpaw comes less than a year after Gyllenhaal dropped 13 kilograms to play creepy video journalist Louis Bloom in Nightcrawler.

“It is extreme what he’s done, absolutely extreme,” says nutritionist Dorota Trupp.

“You can see depression developing, you can see hormonal imbalance – it is putting yourself at high risk.”

Gyllenhaal on the red carpet recently (left) and in Southpaw.

The 34-year-old subsisted on chewing gum and tea to lose weight for Nightcrawler, before switching to a high-protein diet and six-hours-a-day training schedule for Southpaw.

In doing so, Gyllenhaal also risked injury, infection and serious muscular deficiencies, according to experts.

And he’s not alone. Here are the other stars who have risked their health to get into character.

Bradley Cooper

Role: Navy SEAL Chris Kyle in American Sniper.

Weight gain: 18kg of fat and muscle.

How he did it: He ate more than 5000 calories a day and did lots of weight training. At his peak, Cooper could lift close to double his body weight.

“It was a real shock to my body. If it’s pizza and cake, that’s one thing. Putting 6,000 calories a day in your body gets old quick,” Cooper said of his diet.

Why it’s dangerous: “This is not your path to good quality weight gain,” dietitian Tim Crowe, Associate Professor in the Faculty of Health at Deakin University, says.

“It is hard to eat 6000 calories a day of pure healthy food.”

Ms Trupp adds that Cooper’s liver could very easily have been overwhelmed by the high fat and sugar content of the food he was consuming.

Anne Hathaway

Role: Fantine, a starving prostitute, in Les Miserables.

Weight loss: 11kg in the space of a month.

How she did it: Hathaway survived on what she described as a “rabbit food” diet – mainly vegetables – that left her so fragile she broke her arm in a fall.

“I was on a starvation diet to look like I was near death in a film,” Hathaway explained of her gaunt appearance.

Why it’s dangerous: “She is running the risk of developing nutritional deficiencies and dangerous muscle loss,” Ms Trupp says.

“Particularly with women this can cause hormonal imbalance, which can effect their menstruation.

“The healthy recommendation [for weight loss] is around 1.5 kilos a week so she is way above this.”

Matthew McConaughey

Role: AIDS sufferer Ron Woodroof in Dallas Buyers Club.

Weight loss: 21kg

How he did it: “It was tough going, I’m not going to lie. The dieting was pretty hardcore. I was losing 7lb every week,” McConaughey said of preparing for his Oscar-winning role.

McConaughey, who is 183cm tall, survived on a diet of Diet Coke, egg whites and a piece of chicken a day.

The weight loss was not without its side effects, with the 45-year-old admitting, “As soon as I hit 143lb [64kg], I started losing my eyesight.”

Why it’s dangerous: “This was done really badly,” Professor Crowe says.

“The sorts of food they chose are not giving the body any quality nutrition at all.

“It is so surprising that with all these actors they haven’t got some good advice from professionals because with the right supplements this can be done relatively safely.”