Matt Damon implored fellow Hollywood star Chris Hemsworth not to follow his "dangerous" starvation diet when the actor turned to him for weight loss advice for his role in the movie 'In The Heart Of The Sea'.
Hemsworth, known for his muscular role as superhero Thor, slimmed down dramatically to play a shipwrecked sailor but was warned off the diet that Damon used to lose 50lbs for his 1996 film 'Courage Under Fire' - which left him taking medication for a year for adrenal gland damage.
He said Damon told him: "Look, I had no education then. It was basically eat nothing for four months."
Hemsworth added: "He said it's dangerous to do it that way. He told me there are much better ways of doing it, so seek the advice of a nutritionist."
Hemsworth plays First Mate Owen Chase in the tale of the real-life Nantucket whaling ship The Essex, which was destroyed by a whale in 1820, leaving its crew to survive for 90 days at sea. It was the inspiration for Herman Melville's classic novel 'Moby Dick'.
Alongside co-stars Cillian Murphy, Tom Holland and Benjamin Walker, the cast were put on a diet that saw their calories cut to as low as 500 a day to drop more than 30lbs each.
"It was an us-against-the-world kind of thing," he said of the cast's bonding experience.
In addition to the weight loss, he said the film - which also stars Irish actor Brendan Gleeson - replicated the "brutal and raw" conditions of life at sea.
"We were wet 90pc of the time and exhausted," he said. "Really cold when we shot in London and really hot when we shot in the Canary Islands - you're in rags most of the time."
But his wife, model Elsa Pataky, was the most glad when the diet came to an end, and he admitted: "She prefers me putting on the weight - doesn't have to put up with the mood swings. We didn't snap at one another on set but you're sensitive to the most trivial things."