Chris Hemsworth unrecognisable after dramatic weight loss for movie role

Many fans have expressed shock after Australian actor Chris Hemsworth looked dramatically different in a photo he had shared on Monday (Nov 23).

In the photo posted on Instagram, the 32-year-old appeared scraggly with long, unkempt hair, and also looked badly sunburned.

The accompanying caption read: "Just tried a new diet/training programme called "Lost at Sea". Wouldn't recommend it."

People Magazine reported that he had shed his usual buff physique for a much leaner one by going on a 500-calorie diet to prepare for his role in the movie In the Heart of the Sea, which tells the story of the survivors of a shipwrecked crew following a whale attack in 1820.

"We have to shoot the really skinny stuff where we drop down to 5, 6, 700 calories a day, (for) a good three or four weeks and it's going to be pretty uncomfortable," he said in an ET Online report.

500 calories a day is far below the recommended daily calorie intake for adult males his age, which ranges from 2,185 to 3,560 depending on activity levels, according to the Health Promotion Board.

Hemsworth is known for his fit body in movies such as Thor and Snow White and The Huntsman, and was even chosen by People Magazine as the Sexiest Man Alive in 2014 .

Just tried a new diet/training program called "Lost At Sea". Wouldn't recommend it.. #IntheHeartoftheSea

A photo posted by Chris Hemsworth (@chrishemsworth) on