We are living longer yet growing less healthy. That is the paradoxical conclusion reached by researchers who have found successive generations building up medical problems worse than those faced by their forbears.
Life expectancy has grown dramatically in recent decades as a result of improved nutrition, housing and medical care. But today's 40-year-olds are experiencing problems of excess weight, high blood pressure and diabetes similar to those now in their mid-fifties.
The younger generation is thus 15 years ahead of the older generation on the pathway to increasing frailty, disability and ill health. Ultimately, the effect is likely to be a slowing of the increase in life expectancy or even a reversal, experts say.
For more than a decade doctors have warned that our existing way of life is killing us softly, due to an excess of fat, sugar and salt – and sloth. Two-thirds of the population are overweight or obese and, on present trends, that will rise to 90 per cent by 2050.
Obesity already causes an estimated 9,000 premature deaths a year, and doctors fear its relentless rise could mean the current generation will be the first to die before their parents.
Researchers who followed 6,000 individuals for up to 16 years have charted the consequences of that indolent, calorie-rich lifestyle and found the adults of today are less "metabolically" healthy than in the past.
"The more recently born generations are doing worse than their predecessors," they say, adding: "The prevalence of metabolic risk factors and the lifelong exposure to them have increased and probably will continue to increase."
The study was conducted in the town of Doetinchem in the Netherlands beginning in 1987. The researchers compared the health of those in their twenties, thirties, forties and fifties and then followed up each group to find out how one generation compared with another born a decade earlier.
At the start of the study, 40 per cent of men in their thirties were overweight. But 11 years later, the proportion had grown to 52 per cent among the next generation of men in their thirties. Among women, their weight did not change until the most recent generations when the proportion who were obese doubled in a decade. These "generation shifts" were also seen in high blood pressure, with the prevalence of the condition increasing in each generation for both men and women. The only exceptions were the two most recent generations of men. A similar increase was seen in diabetes in succeeding generations of men, though not of women.
There was no generation shift in high cholesterol, but levels of "good" HDL cholesterol did rise in the oldest two generations. Gerben Hulsegge, of the Dutch National Institute for Public Health, who led the study published in the European Journal of Preventive Cardiology, said the impact of obesity in youth was a critical factor.
"The prevalence of obesity in our youngest generation of men and women at the age of 40 is similar to that of our oldest generation at the age of 55. This means that the younger generation is 15 years ahead of the older generation and will be exposed to their obesity for a longer time."
As smoking has declined in recent decades, there is also likely to be a shift from smoking-related illnesses such as lung cancer to obesity-related diseases such as diabetes.
Dr Hulsegge said: "The decrease in smoking and improved healthcare are important driving forces behind greater life expectancy of younger generations. But it is also possible in the distant future, as a result of current trends in obesity, that the rate of increase in life expectancy may well slow down."
Lifestyle illnesses: The three big killers
Since 1996 the number of people diagnosed with diabetes has more than doubled from 1.4 million to 2.9 million. By 2025 it is estimated that five million people will have diabetes. The illness increases the risk of heart failure, kidney failure, and death – and is one of the biggest health challenges facing the UK.
In the study, the prevalence of diabetes increased in each succeeding generation of men though not of women.
It is one of the most important causes of heart disease, stroke and kidney disease and controlling it is one of the most effective ways of preventing premature death. High blood pressure affects an estimated 12 million people in the UK, one in four of the adult population and one in two of those over 60. In the study, the prevalence of high blood pressure increased in each generation of men and women, except for the two most recent generations of men.
Being overweight or obese increases the risk of heart disease, cancer and a range of other conditions. Two-thirds of people in the UK are overweight or obese and obesity is estimated to cause 9,000 premature deaths a year.
At the start of the study, 40 per cent of men in their thirties were overweight. A decade later, the proportion of men overweight in the next generation of men in their thirties had risen to 52 per cent.