Message fit for couch potatoes
As gyms swell with the optimism of countless New Year resolutions, a message arrives from Germany that will bring cheer to sloths everywhere. What is the key to a long and healthy life? Laziness.
Put forward in The Joy of Laziness - How to Slow Down and Live Longer (Bloomsbury), the message has raised eyebrows among experts studying the science of ageing. At best, they say, the book is a muddled collection of grains of truth that oversimplify what scientists understand about the complex process of ageing. At worst it is dangerous, giving those already living life in the bus lane a handy justification to do little to keep themselves healthy.
The Joy of Laziness has been written by a German father and daughter team. Peter Axt, say the publishers, is a former health sciences expert at Fulda University near Frankfurt, and Michaela Axt-Gadermann is a practising dermatologist. The book begins with an explanation that we are all born with a limited amount of "life energy". If we use it all up quickly - by exercising and getting stressed out - we will die early. If we do very little and live life at a snail's pace, we can eke it out and live much longer.
It's a theory that doesn't find much support in the scientific community. "The idea's been around nearly 100 years and we know that it's wrong," says Tom Kirkwood, co-director of the Institute of Ageing and Health at Newcastle University, England.
The authors illustrate their ideas on "life energy" by looking at how much longer wild animals live if kept in captivity. "While wild animals cover many miles daily in search of food, and consequently are under a great deal of stress, zoo animals lead a very restful and relaxed life," they write, before citing how lions in the Serengeti live only eight years, but can live to the age of 20 in a zoo.
"Laziness and downtime is important for your health. It is well known that lazy animals have the longest life expectancy," says Axt-Gadermann.
But the idea of "life energy" is seriously flawed, says Brian Merry, an expert on ageing at Liverpool University, England. Putting an animal in a zoo has no effect on how quickly it ages, he says, but simply protects it from starvation, disease, predation and so on.
Axt-Gadermann says there are three things we need to do to ensure a longer life. "First, stay cool and calm." Avoiding stress wherever possible helps reduce our levels of stress hormones, which speed up ageing. Second, get enough sleep. And third, eat less or fast for two days a month, as cutting down on calories "is the most effective way to prolong your life and avoid illness," she says.
Kirkwood says the problem with the book is that it undermines well-informed messages about the benefits of exercise.