BEING even moderately obese can cut two to four years off a person's life, research revealed yesterday.
For those classed as severely obese, up to ten years could be wiped off life expectancy, making it as dangerous as smoking, according to a study of almost a million people.
Campaigners said the findings confirmed the dangers of being overweight an
d should encourage people to take action to improve their health.
Scientists assessed the effect of obesity on lifespan by using data on 900,000 adults who took part in 57 separate studies.
In the Lancet, they reported a clear association between high body mass index (BMI) scores and premature death.
BMI is calculated by dividing a person's weight in kilograms by their height in metres squared.
The study found that having a BMI above the "ideal" range of 22.5 to 25 led to higher death rates. Above 25, every extra five units on the BMI scale increased mortality by around a third.
The investigation, called the Prospective Studies Collaboration, pooled information on 894,576 individuals, mostly from western Europe and North America, with an average age of 46 and an average BMI of 25.
As well as looking at overall death rates, the researchers linked BMI scores with common causes of death through illness.
Each additional five BMI units corresponded with a 40 per cent increase in deaths from heart and artery disease and strokes, an increase of 60 per cent to 120 per cent from diabetes and liver or kidney disease, a 10 per cent increase from cancer and a 20 per cent increase from lung disease.
Moderate obesity, corresponding to a BMI range of 30 to 35, reduced survival by between two and four years.
Severe obesity, in the 40 to 45 BMI range, cut lifespans by eight to ten years – comparable to the effects of smoking.
Higher death rates were also seen among people with BMIs below the optimum range, mainly due to smoking-related diseases, according to the Oxford University team led by Professor Sir Richard Peto and Dr Gary Whitlock.
Dr Whitlock said: "Excess weight shortens human lifespan. If you are becoming overweight or obese, avoiding further weight gain could well add years to your life."
The authors, funded by the Medical Research Council, Cancer Research UK and the British Heart Foundation, stressed that even overweight people who could not slim could extend their lives by not getting fatter.
Sara Hiom, of Cancer Research UK, said: "This study confirms that excess weight increases the risk of dying from cancer.
"Moderate obesity is becoming worryingly common in the UK, and these factors combined are great cause for concern."
Professor Peter Weissberg, the medical director of the British Heart Foundation, said: "This is the latest and most convincing demonstration of the close relationship between being overweight and poor heart health."
