Less is more (Image: Eisebhut & Mayer - Wein/Foodpix Artpartner-Images/Getty)

IN GREEK mythology, the tale of the Trojan prince Tithonus is a tragic one. His lover, the goddess Eos, asks Zeus to grant him eternal life, but forgets to specify eternal youth. Time passes, and while the goddess of dawn stays young and beautiful, Tithonus degenerates into bedridden senility. Eventually Eos shuts him in a chamber of her celestial palace, where his feeble voice can be heard begging for death.

Dreams of eternal youth feature in many cultures throughout history, but it was only in the 20th century that research into longevity really began. Much about ageing is still mysterious – we don’t even know the underlying reasons why we journey into old age. There are many lines of enquiry into how to live longer, though, with one of the most intriguing being calorie restriction: in effect, going on a lifelong diet.

Calorie restriction dramatically extends not only the lifespan of laboratory animals, but also their “healthspan” – how long they live free of disease. On the assumption that it has the same effect in people, some individuals have already adopted a restricted diet. The latest evidence suggests that while calorie restriction is indeed beneficial for humans, when it comes to lifespan extension, it may not be the whole story.

The good news is that we might be able to delay ageing without cutting our food intake. “There’s a definite possibility that if you balance the diet correctly, a longer lifespan can be achieved without full food restriction,” says Matthew Piper, a researcher into ageing at University College London.

There is a definite possibility that if you balance …