This is the moment a man once dubbed the world's heaviest teenager walked for the first time in his life.

Khaled Mohsen Al Shaeri, now aged 24, from Saudi Arabia, weighed an incredible 610kg (1,345lbs) at his heaviest.

He has now successfully lost 320kg (700lbs) following an intensive hospital fitness routine.

This is the moment Khaled Mohsen Al Shaeri, once dubbed the world's heaviest teenager, walked for the first time in his life after losing more than 700lbs from his previous weight of 1,345lbs

Video posted online shows him walking with the help of a Zimmer frame after shedding two thirds of his weight

Doctors who treated him the capital Riyadh said Shaeri has shed more than two thirds of his weight and that he is still on a health programme to lose more.

And now all his hard work was not in vain after Shaeri achieved an incredible milestone in his recovery - a video has been posted online showing him walking with the help of a Zimmer frame.

Shaeri was nearly 610kg when he was taken by medical helicopter to the King Fahd Medical City in Riyadh for treatment.

The treatment for the young man had been organised at the request of the late King Abdullah in 2013.

Nearly 30 medical staff members and civil defence men joined hands to lift the boy with a special crane ordered from the U.S. and flew him to the capital.

Saudi Civil Defence members use a forklift to move Khaled Mohsen Shaeri from his house in the Saudi city of Jizan to be airlifted to the capital Riyadh for medical treatment in August 2013

Nearly 30 medical staff members and civil defence men joined hands to lift the boy with a special crane ordered from the U.S. and flew him to the capital

Khaled Mohsen Al Shaeri, now 24, from Saudi Arabia, weighed an incredible 610kg (1,345lbs) at his heaviest

Shaeri was nearly 610kg when he was taken by medical helicopter to the King Fahd Medical City in Riyadh

A huge operation: Saudi Arabian king sends aircraft to take obese man weighing 1,345 pounds to hospital

Nearly 30 medical staff members and civil defence men joined hands to lift the young man with a special crane ordered from the U.S. and flew him to the capital