Weight loss

Moderate obesity takes years off your life

zone image Can reduce life expectancy as much as smoking

Being severely obese can reduce your life expectancy as much as smoking, according to research carried out by Oxford University scientists. Worryingly, they also found that moderately obese people had their lifespan shortened by three years.

Scientists analysed results from 57 studies carried out in countries in Europe and North America, involving almost a million people, to investigate how obesity affected lifespan.

They used body mass index (BMI) as a measure of obesity. BMI is calculated by dividing a person’s weight in kilograms (kg) their height in metres squared (m).

Healthy BMIs fall within the 22.5 to 25 range. A person with a BMI of 30 to 35, is regarded as moderately obese; a BMI of 40 to 50, severely so. Though not perfect, BMI is a useful tool for assessing the extent to which fatty tissue can cause ill health.

The results showed that mortality was found to be lowest in the BMI rage 22.5-25. An increase in BMI of 5, on average , was associated with a 30% increase in mortality. Moderately obese people (BMI 30 to 35, now common in the UK), had their lifespans reduced by three years.

Severe obesity (BMI 40 to 50, still uncommon in the UK) reduced life expectancy by about 10 years, similar to the effect of lifelong smoking.

The increasing death rates were found to be caused by obesity related illnesses including heart disease, stroke, diabetes, liver and kidney disease and cancer.

‘Excess weight shortens human lifespan. In countries like Britain and America, weighing a third more than the optimum shortens lifespan by about 3 years. For most people, a third more than the optimum means carrying 20 to 30 kilograms [50 to 60 pounds, or 4 stone] of excess weight. If you are becoming overweight or obese, avoiding further weight gain could well add years to your life,’ said Oxford epidemiologist Dr. Gary Whitlock.

This article was published on Thu 19 March 2009

Image © Sheila Eames - Fotolia.com

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