But he does not view the experience as a culture clash. Rather, he said, it reflected mean and stingy treatment by his host family, whose broken English made it difficult to communicate. "The weight loss concerned me, but I wanted to stick out the whole year," he said in an interview at his family's home outside Augusta. Friends and teachers at his English-speaking school in Egypt urged him to change his host family, but he stayed put after being told the other home was in a dangerous neighbourhood of Alexandria.

After returning to the US, he was hospitalised for nearly two weeks. The 17-year-old has regained about 9kg, but his parents say he's not the same boy he was when he left under the auspices of AFS Intercultural Programs. "He was outgoing, a straight-A student, very athletic. Now, he's less spontaneous and more subdued," said his mother, Elizabeth McCullum, who was shocked when she met her son at the airport on January 9 and saw he had lost one-third his weight.

Jonathan McCullum's parents said the exchange program should have warned them that students placed with Coptic families would be subject to dietary restrictions. Marlene Baker, communications director at AFS headquarters in New York, declined to discuss McCullum's experience. She referred calls to the program's lawyer in Portland, Patricia Peard, who said she could not comment on McCullum's case because of the potential for a lawsuit. McCullum said his host family gave him only meager amounts of food, and his condition worsened during the last seven weeks, when the family observed a fast limiting the amount of animal protein he was given.

The host family was a couple with two younger boys and a daughter who was in the U.S. on an AFS exchange. McCullum said the parents gave him the smallest food portions, hid treats in their bedroom and complained that the cost of his upkeep was more than they spent for their daughter when she was home. The host father, Shaker Hanna, rejected McCullum's story as "a lie," suggesting that he made it up because his parents were hoping to recover some of the money they paid for his stay as compensation.

"The truth is, the boy we hosted for nearly six months was eating for an hour and a half at every meal. The amount of food he ate at each meal was equal to six people," Hanna said. He added that the boy was active, constantly exercising and playing sports. Hanna, an engineer, said his family went out of its way to prepare special foods, including fish and chicken, for McCullum during the fast periods. McCullum disputes that. The family served meat early in his stay, he said, but that ended during the fast period.

He said he never got breakfast and his first food of the day usually was a small piece of bread with cucumbers and cheese that he would take to school for lunch. There was a late-afternoon dinner consisting of beans, vegetables and sometimes fish, and a snack of bread later in the evening. McCullum sometimes bought food, but at one point was reduced to stealing it from a supermarket. He was caught, but the store accepted the small amount of money he had and let him go.

Still, McCullum did not complain to his parents. His father suspects he may have fallen victim to Stockholm syndrome, in which people start to feel a sense of loyalty to those who victimize them. McCullum's parents first sensed that something was amiss shortly before Christmas, when they got emails from their son and one of his teachers about seeking a new host family. They also saw a picture of him on Facebook indicating he had lost a lot of weight. In early January, the teacher sent another e-mail saying McCullum was "in bad shape" and "really, really NEEDS to go home."

The McCullums said AFS provided false assurances that he had seen a doctor and was in excellent health. AFS, a nonprofit formerly known as American Field Service, is one of the largest and oldest organizers of student exchanges. Since its founding as an ambulance corps during World War I, the agency has arranged exchanges for 325,000 American and foreign students from more than 50 countries.

The McCullums said AFS discourages parents from telephoning or e-mailing their kids abroad, believing the distraction would run counter to the program's goal of immersing them in local culture. "They told us to have as little contact as possible, and we bought into it," Elizabeth McCullum said. She said she had confidence in AFS, regarding it as "the gold standard" of exchange programs, but now is aware that things can go terribly wrong. The Committee for Safety of Foreign Exchange Students, a nonprofit advocacy group, said the exchange programs are rampant with instances of abuse and neglect.

"This is not an isolated incident. I'm aghast but I'm not shocked," the committee's director, Danielle Grijalva of Oceanside, Calif., said after hearing McCullum's story. The McCullums are considering a lawsuit. David McCullum expressed concern about the long-term physical and psychological effects on his son. "Someone needs to be held accountable, and I would like someone to say, 'I'm sorry.'"

Jonathan McCullum is recovering and recently went snowboarding with friends. He plans to return to school in the fall, rejoin the soccer team and eventually study to be a doctor. Despite the ordeal, he has not soured on foreign travel: He wants to visit Zimbabwe this summer as part of a volunteer program to build homes and trails. AP