Story highlights In August, King Abdullah ordered Khalid bin Mohsen Shaari to be treated in Riyadh, the capital

He then weighed 1,345 pounds and had not left his bed for three years, magazine says

Heart and lungs are better, and he has less inflammation and stronger muscles, doctor says

Shaari still can't move on his own and uses a mechanized pulley to sit on a big wheelchair

A Saudi man has lost more than 700 pounds (320 kilograms) -- more than half his body weight -- since Saudi Arabia's King ordered him hospitalized in August, according to a Saudi magazine that interviewed him at a hospital.

In August, King Abdullah ordered Khalid bin Mohsen Shaari , who then weighed 1,345 pounds (610 kilograms), to undergo treatment in the capital, Riyadh. Shaari, estimated to be in his late teens, was unable to move by himself and was transferred from Jazan in southern Saudi Arabia.

Dr. Aa'ed al-Qahtani, head of the medical team overseeing Shaari's treatment, told Sayidaty magazine in a recent interview that Shaari's health is continuing to improve at a steady rate. He has improved heart and lung function, reduced inflammation and improved muscle strength, including the ability to move his feet, he said.

A massive custom-made wheelchair was built to help Shaari become more mobile and aid his physical therapy, al-Qahtani said. Shaari still cannot move on his own and needs to use a mechanized pulley to sit on the chair. Before being taken out of his house on a forklift, Shaari had not left his bed for three years, the magazine said.

In photos published in the magazine, which has launched an obesity awareness campaign, Shaari is shown smiling and holding up a victory sign. Doctors say his spirits have constantly remained high. Dr. Abdeljabbar al-Yamani, the managing director of King Fahd Medical City, has dubbed him "the smiling man."

His mother has stayed with him since he was admitted.