We all know Chris Hemsworth for looking like a ridiculously chiselled and shredded Norse god, but the Thor and Avengers star recently slimmed down drastically to play a 19th-century sailor stranded at sea for In the Heart of the Sea.

Sharing a photo on social media, Hemsworth revealed his dramatic transformation: “Just tried a new diet/training program called ‘Lost at Sea,’” he wrote on Twitter. “Wouldn’t recommend it.”

Hemsworth revealed earlier this summer that some seriously gruelling effort went in to losing all that poundage. He said that he was already considerably under his “Thor weight” after slimming down for the thriller Black Hat, and losing the last 15 pounds for In the Heart of the Sea was exhausting.

“When you’re already starting off lean, its brutal to chew through that kind of weight,” Hemsworth said. “Every pound feels like a kilogram.”

Hemsworth stars as real-life first mate Owen Chase, who served on the whaling ship Essex and was stranded at sea after a whale destroyed the ship. To play men cast adrift with no food, Hemsworth and his co-stars reduced their diets to a measly 500 calories a day.

“They had to work out every day, even on shooting days,” director Ron Howard told EW. “Because they had to lose the weight pretty fast and they had to lose it safely. They needed to keep burning the calories and we also needed that sinewy strength that was more of that era, as opposed to a kind of cut, buff look.”

Watch the epic final trailer for In the Heart of the Sea below: