Martin Clunes: Islands of Australia (ITV, 8pm)

HAVING made his reputation in 1990s sitcom Men Behaving Badly, Martin Clunes discovered that even in the little-known islands off the coast of Australia, he is far better known as the bombastic Doc Martin.

When Clunes paid a visit to Australia's remote Norfolk Island, nearly 1,500km from the mainland, the local reaction took him by surprise.

Doc Martin, it turns out, is a big hit Down Under, and feverish fans of the Cornwall-set series – known as 'Clunatics' – had gathered at the island's small airport to greet its star.

"I had never felt so famous. It was like being one of the Beatles," says Clunes, who has played grumpy doctor Martin Bamford in the comedy-drama since 2004.

This three-part series sees the genial explorer faced with around 8,000 islands to choose from and concentrating on 16, with the help of local and BBC researchers, that are capable of providing an insight into the diversity, history and challenges of island life.

"Each island is a microcosm that tells us something different about our world," says Clunes. "Australia's islands have it all: exotic creatures, spectacular marine life, and of course the different people who inhabit them.

"Whether they're relative newcomers or they've lived there for generations, these are the resourceful, extraordinary people who call these islands home. This is my voyage around the adventure playgrounds, the best-kept secrets and the astonishing surprises of the islands of Australia."

He begins 16 miles off the coast in the warm waters of the Arafura Sea, which are home to the so-called islands of smiles – the Tiwi Islands. They're populated by more than 3,500 people whose ancestors have been there for millennia. Thanks to their remote setting, the region has remained largely untouched by outside influences, allowing its distinctive Aboriginal culture to flourish.

"It's been a real privilege to visit the Tiwi Islands," says Clunes. "Not only because of the incredibly warm welcome I've had from everyone, but also to see an indigenous community celebrating their ancient history while at the same time embracing the 21st century and making it work for them."

His next stop is the Ningaloo Reef. It may not be as well known as the Great Barrier Reef, but it is widely regarded as the country's greatest natural wonder – and it's a lot less crowded, which allows Clunes to swim amongst its colourful flora and fauna.

How to Lose Weight Well (C4, 8pm)

DR Xand van Tulleken, Hala El-Shafie help more dieters tackle weight-loss regimes. They begin by meeting Stefanie and Jade from Harrow who have ten days to slim down before the launch of their clothing label. Jade tests a low-fat diet, while sugar addict Stefanie must survive on foods that don't contain the sweet stuff. Later, the duo challenge fast-food fan Matt from Redditch to test a 'warrior' diet, which involves eating like a Roman soldier. And finally Rob from the Wirral tries a "Sleeping Beauty" regime, in the hope that sleeping more will help his body optimise the hormones that control his metabolism and appetite. But will there be a happy ever after as far as his diet is concerned?

Sugar Free Farm (ITV, 9pm)

THE celebrities are only four days into the challenge and tensions are already beginning to increase. Also rising is Gemma's weight, which she suggests may be down to her gaining muscle. Comedian and novice cook Joe is in unfamiliar territory in the kitchen, but feel a bit more relaxed doing a spot of Otrout whispering' on a fishing trip. Meanwhile, Alison and Stavros make cheese and butter from scratch, and a disgusted Ann discovers what really goes into the low fat spreads she eats every day. Then, as Peter returns to the farm following his medical drama, Alison suffers a dizzy spell and is referred to hospital for a full diabetes test. Finally, back out in the chicken sheds, Gemma's quest to find a farmer husband continues.

Viv Hardwick