Ah, summer, the season when we are offered the chance to flirt with the idea, if not the reality, of a new diet every week.

This year has brought a few startling new additions to the panoply of lifestyle fads. First, the Olympic Games Plan, a relentless course of Coca-Cola and McDonald's cheeseburgers which, one assumes, should make a sprint champion out of the most idle couch potato.

Actually it's worth noting that there was a man called the McRunner who lived on a diet of McDonald's and then ran the Los Angeles marathon, but you only have to watch Supersize Me to see it's a diet that requires caution.

Now we have the astronaut diet, drawn up by Nasa for travel to Mars in 2030. This is a vegetarian affair since it isn't possible to preserve meat and dairy over the two-and-a-half year stretch in space, but the menu had me salivating like a Pavlovian dog.

"For lunch they could potentially have a marinated tomato salad accompanied by, perhaps, a soup and sweet potato fries," says Mary Cooper, research scientist. "And then, for dinner, tofu mushroom stroganoff accompanied by spinach bread and a nice dessert, such as spice caramel coffee cake or ultimate lemon cake."

Compared with the grapefruit diet, or the relentless protein of the Dukan, even a Mars-a-day diet starts to appeal.

On the plus, if you take the lifestyle to its full and the caramel cake does pile on the pounds, no-one is going to notice when you're sporting a Michelin Man-style space suit. Will it take off here on planet earth? No celebrity has got behind it yet, but give it a few more months and someone is bound to be swearing by it.