After a four-day search, Greek officials said on Sunday they had found the body of Michael Mosley, a British medical journalist and documentary maker who disappeared last week while on a trip on the Greek island of Symi.

His body was found on a beach in Agia Marina, said the mayor of Symi, Eleftherios Papakalodoukas.

His disappearance had prompted an extensive search that called in firefighters, police officers and volunteers. The authorities also used dogs and drones, and the Greek coast guard also joined the effort as fears escalated that Mr. Mosley had drifted out to sea.

Mr. Mosley, 67, a BBC journalist, had arrived on Tuesday on Symi, part of the Dodecanese islands in the Aegean Sea, for a weeklong trip. He told friends at Agios Nikolaos beach on Wednesday afternoon that he would walk back to his accommodation in Symi town, the local authorities said.

The walk is about two miles, depending on the route taken. When hours had passed with no sign of Mr. Mosley, his wife, Clare Bailey Mosley, reported him missing to the police.

Search efforts shifted north, toward Agia Marina, on Friday after footage emerged from security cameras in the village of Pedi — about halfway between Agios Nikolaos and Symi town — showing what appeared to be Mr. Mosley carrying an umbrella.

The terrain in the north, above Agia Marina, is significantly more rugged and dangerous.

The police said that Mr. Mosley did not have his phone on him during the walk, and was last seen by a witness at a bus stop in Pedi.

Over the years, many British viewers relied on Mr. Mosley, a longtime investigator of science and health, for his myth-busting advice on diet, exercise and sleep. Trained as a doctor before venturing into television, Mr. Mosley hosted the popular BBC health podcast “Just One Thing” and appeared on the show “Trust Me, I’m A Doctor.”

He produced a variety of health and science programs for the broadcaster, and often offered himself up for experimentation in the documentaries he presented. He swallowed parasites and trialed magic mushrooms, but he was most widely known for popularizing the 5:2 diet, a form of intermittent fasting that involves five days of normal eating and two days of fasting each week.

He was nominated in 2002 for an Emmy for “The Human Face,” a series examining the science behind beauty.

More recently, he had released two series with the British Channel 4 broadcaster investigating obesity in Britain and the nutrition behind the grocery shopping of everyday consumers. He had toured Britain this year with his wife, also a doctor and health columnist, with an interactive live show focused on healthy living.