A physicist who fasted for 218 days in Lafayette Park across from the White House to protest nuclear weapons and U.S. foreign policy says he ended his fast to concentrate on his campaign for president.

"I decided that I might be able to get as much done by campaigning for the presidency," former NASA scientist Charles Hyder said Friday. "If that's not true, I can always start fasting again."

Hyder, 56, a former adjunct physics professor at the University of New Mexico, said that he weighed 315 pounds when the fast began Sept. 23 and that he is now down to 140 pounds.

He said he had consumed nothing but salt and water since the start of the fast, a statement medical authorities questioned.

When Hyder began the fast, he said he would not eat until the United States agreed to disable and dismantle all of its nuclear weapons by 2000, to refrain from the use of military force outside the country and to make a good-faith effort to persuade the rest of the world to make the same commitments.

Soviet President Mikhail S. Gorbachev sent a message to Hyder in February, urging him to end his fast, saying his "spiritual strength is needed" to work for arms control.