British TV presenter Dr Michael Mosley, known for popularising the 5:2 diet, has gone missing while on holiday with his wife on the small Greek island of Symi.
A search and rescue operation is under way, including a police dog and a drone covering hard to reach areas, BBC News reported on Friday.
What do we know so far?
Mosley, 67, and his wife, Dr Clare Bailey, arrived on the small Greek island on Tuesday (local time) where they were to spend a week with a couple who have a house in the village, reported the Daily Mail, for whom Mosley is a columnist.
Together, the couples took a boat up the coast on Wednesday morning, stopping at St Nicholas beach.
Mosley went for a swim before setting off on a walk back to the home they were staying at in the centre of the island at 1.30pm on Wednesday.
His phone was found in the place he was staying. His wife reported him missing at 7.30pm that night when he hadn't returned.
A post shared in a local Facebook group was appealing to anyone on the island of about 2500 people who may have seen Mosley.
It read: "Have you seen this man? He set off to walk back from St Nick's at about 13.30 and failed to make it home. His friends are concerned as it is 6 hours since they last saw him. His name is Dr Mike Mosley and he is a familiar face for many British people."
What could have happened?
Greek police spokesman Constantina Dimoglidou told the Daily Mail: "He may have slipped, tripped, fallen, even been bitten by a snake, remaining injured somewhere.
"There is just no trace of him. None whatsoever. And that means that for us at least, every potential scenario is open and being investigated."
Dimoglidou said: "We're looking everywhere for him … It's rugged terrain with high spots, so it's possible that he fell."
A rescue operation on Friday focused on the Pedi area of Symi after a woman saw him there days earlier, the island's deputy mayor Ilias Chaskas told BBC News.
Who is Dr Michael Mosley?
A BBC science journalist and author, Mosley is one of the most famous doctors on television. He has written several popular books on intermittent fasting and blood-sugar diets and was one of the first people to make popular the 5:2 diet.
He is an Emmy nominated host, appearing on NZ screens in the show, Trust Me, I'm a Doctor along with a long list of television and radio interviews locally.
Mosley, a trained GP, is known for putting his body on the line in the name of research. He is one of the leading advocates for intermittent fasting as well as low carbohydrate and ketogenic diets.
He published a book on using diet to improve sleep, called Fast Asleep , after revealing he suffered from chronic insomnia. Another book, The 8-week Blood Sugar Diet, was published at the end of 2015.
He has a podcast called Just One Thing which unpacks "simple things scientifically proven to improve your life" and is currently a regular columnist for the Daily Mail.
The father-of-four visited New Zealand with his wife in 2023 to talk about weight loss, sleep, wellness, and how the body works in his live show, A Life Changing Experience.
Ahead of that visit, Mosley spoke to The Project NZ. Asked if anyone would want to live to 101, Mosley told host Jesse Mulligan: "What most of us want to do is lead a long and reasonably healthy life and then get run over by a bus perhaps while kite surfing or getting eaten by a shark. That's my ambition anyway."