By Leigh Parry
Extra body weight shortens your life span, according to a new study of 900,000 adults.
British researchers found that body-mass index (BMI) above the ideal range of 22.5-25 led to increased mortality rates, with each extra five kg/m2 raising overall mortality by one third.
Dr Gary Whitlock from the University of Oxford said excess weight shortened human lifespan.
“In countries like Britain and America, weighing a third more than the optimum shortens lifespan by about three years,” he said.
“For most people, a third more than the optimum means carrying 20 to 30 kg of excess weight.
“If you are becoming overweight or obese, avoiding further weight gain could well add years to your life.”
Researchers used data from 57 prospective studies involving participants from western Europe and North America for the research, published in The Lancet.
Mortality was lowest in the 22.5-25 BMI range, which means that if a person was 1.7m (5 feet 7 inches) tall, his or her optimum weight would be about 70 kg.
The authors said a typical middle-aged person could gain about two years of life expectancy by avoiding a BMI increase from 28 to 32.
* Keeping a healthy weight and reducing stress could prevent the chromosome changes associated with ageing in women, according to two papers published in Cancer Epidemiology Biomarkers and Prevention.
The pilot study, by researchers from the National Institutes of Health, USA, was part of the long-term Sister Study looking at women and breast cancer.
The study examined the length of telomeres, or the repeated DNA sequences that cap the ends of a person’s chromosomes.
It found that factors such as obesity and perceived stress could shorten telomeres and accelerate the aging process.
One study showed that women who were obese for a long time had reduced telomere length.
The other found that stress can also impact of telomere length.
Lead author Professor Christine Parks said the difference in telomere length was most striking when researchers looked at the relationship between perceived stress and telomere length among women with the highest levels of stress hormones.
“Among women with both higher perceived stress and elevated levels of the stress hormone epinephrine, the difference in telomere length was equivalen to or greater than the effects of being obese, smoking or 10 years of aging,” Professor Parks said.
Researchers also found that the effects of stress may be stronger in women aged more than 55 years.
The Lancet, Early Online Publication, 18 March 2009. doi: 10.1016/S0140-6736(09)60318-4
Cancer Epidemiology Biomarkers & Prevention, March, 2009;18(3):816-20; 18(2):551-560
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