As gyms swell with the optimism of countless New Year's resolutions, a message arrives from Germany that will doubtless bring cheer to sloths. What is the key to a long and healthy life? Laziness. Put forward in the book "The Joy of Laziness -- How to Slow Down and Live Longer," the message has raised eyebrows among experts studying the science of aging. At best, they say, the book is a muddled collection of grains of truth that oversimplify what scientists understand about the complex process of aging. 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" was 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 practicing 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, codirector of the Institute of Ageing and Health at Newcastle University.
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. Arctic polar bears may last only 20 years in the wild, but 40 in captivity. "Laziness and downtime are important for your health. It is well known that lazy animals have the longest life expectancy," says Axt-Gadermann, who adds that priests, nuns, monks and artists also have long lives.
But the idea of life energy is seriously flawed, says Brian Merry, an expert on aging at Liverpool University. Putting an animal in a zoo has no effect on how quick it ages, he says. "A blue tit in your garden has about a 50 percent chance of dying in its first year. Put it in an aviary and it might last up to 12 years. What you're doing is exactly what we've done for ourselves. You're taking it out of the natural environment where individuals die mainly through starvation, disease, predation, accidents and so on and you're protecting them from all those things. You're not doing anything to slow their aging."
The book goes on to warn against the dangers of too much exercise. Physical exertion increases the production of free radicals -- an extremely reactive form of oxygen -- that damage our bodies and so speed up aging. But while free radicals are certainly suspected of playing a major role in the aging process, exercising is not believed to speed aging because of how the body responds when we are physically active. "It's true that if you're working yourself harder, you're burning up oxygen, and it is through burning oxygen that you contribute some of the damage that makes us age, but what happens when you stress yourself with exercise is that you boost your body's capacity to handle the damage that these free radicals cause," says Kirkwood. "If anything, you end up being better off."
He concedes that too much exercise can be a bad thing, but how much is too much? It depends on the individual. But push too much and you are likely to damage joints so much they can't recover. Some scientists suggest that overexercising can also weaken the immune system. "Supreme athletes sometimes get very obscure viral infections that can end their careers," says Merry.
Having warned of the dangers of doing too much exercise, the book outlines how staying calm is essential for a longer life. By avoiding stress -- and what better way to do that than by sitting around and doing nothing -- levels of stress hormones such as cortisol will be kept to a minimum, the authors say.
Cortisol certainly can have health effects, suppressing the immune system and possibly damaging certain types of cells in the brain, but most of these effects are believed to become a problem only when a person is stressed for a long time, rather than in brief bursts. "When the body is subjected to mild stresses, the cells turn up their natural defenses. If a body is left in a completely unstressed state, it doesn't do as well as if you apply a little bit of stress," says Kirkwood.
If avoiding stress is the authors' shield against aging, laughing is their sword. And not without good reason. Laughing, they say, releases the feel-good chemical serotonin that makes us feel happy and relaxed. "There is evidence that laughing is good for you -- certainly being able to laugh at life does help you to age better," says Kirkwood.
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 aging. 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.
According to Kirkwood, the main problem with "The Joy of Laziness" may be the message people take from it. "The idea that we should learn to relax if we're living a very pressured and stressed life is entirely right, but the reasons given in the book for arguing against the benefits of exercise simply don't hold water." If people exercise less, they are more likely to suffer from obesity and cardiovascular disease and suffer muscle wasting as they get older, all of which will severely impact on their independence and the quality of their lives. "Things need to be stimulated and used in order to keep them in tiptop form," he adds.
"A book like this can be quite damaging. There's a lot of evidence that exercise is beneficial for healthy aging and for many people it's already a struggle to do any exercise. Anything that undermines the well-informed message about the benefits of exercise is potentially very damaging because it provides an excuse. It's the copout that all too many people will jump at," Kirkwood warns.