By Phil Stewart

WASHINGTON (Reuters) - New Guantanamo Bay U.S. prison guidelines describe hunger striking detainees as undergoing "long term non-religious fasting," a copy of the document obtained by Reuters shows.

Two U.S. military officials, speaking on condition of anonymity, said on Wednesday the change in terminology helps differentiate between detainees with medical conditions caused by malnourishment, and political protesters who were at or above their ideal bodyweight.

The change follows headline-grabbing hunger strikes by detainees last year which drew renewed attention to President Barack Obama's frustrated efforts to shutter the facility on a U.S. military base in Cuba.

The title of the new standard operating procedure, "Medical Management of Detainees with Weight Loss," replaces "Medical Management of Detainees on Hunger Strike" from March 2013.

The previous guidelines mentioned "hunger strikes" frequently, but the new ones totally exclude the term and only makes one passing reference to the word "hunger."

"It's not our job to feed into their political protests. It is our job to protect their health and keep them safe," one U.S. military official said. "And the new (Standard Operating Procedure) gives us a much better focus on which detainees are actually at medical risk."

The U.S. military decided last year to stop detailing how many of its 155 detainees at Guantanamo Bay are refusing to eat.

A U.S. appeals court in February declined to halt the forced feeding of hunger strikers in Guantanamo Bay but ruled that the prisoners have the right to sue over the procedure and other aspects of how the U.S. military treats them.

Human rights advocates and many doctors call forced feeding a violation of personal liberty and medical ethics. Designed to keep hunger strikers alive, the procedure involves feeding them liquid meals via tubes inserted into their noses and down into their stomachs.

The U.S. military has defended the practice as has President Barack Obama, telling a news conference last year, "I don't want these individuals to die.

(Reporting by Phil Stewart; Editing by Richard Chang)