Friday, March 20, 2009

Being overweight 'can reduce lifespan by three years'

The journal abstract is here. This is an analysis of a large number of studies (though of unknown representativeness) and confirms the usual finding that people of middling weight are the healthiest. What is stressed below are extreme cases, however. The statistics actually provided by the study suggest that the overall correlation between weight and ill health is very weak

Being four stone overweight can cut your life by up to three years, according to a new study. Severely obese people can lose 10 years from their life, researchers found: the same effect as long-term smoking. Almost one in four people in Britain are now obese, official statistics show, and experts predict that the problem will mushroom in coming decades.

The latest study looked at the effect that weight had on the lifespan of almost 900,000 men and women. It found that those with the lowest deaths rates had a "normal" weight, judged to be a Body Mass Index (BMI) of between 22.5 and 25. BMI is a ratio of weight in kilograms versus height in metres.

For every five points, or one band on the BMI scale, above a healthy weight, overall risk of death increased by almost one third, 30 per cent, the study found. Jumping an entire band caused death rates from diabetes, liver and kidney disease to increase by between 60 and 120 per cent. Deaths from heart disease and stroke rose by 40 per cent, while lung disease increased by 20 per cent and cancer 10 per cent.

Dr Gary Whitlock, from the University of Oxford, who led the trial said: "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 30kg - 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."

He and his team looked at 57 previous studies to make their calculations. Those who had a low BMI also had a higher death rate, they found, mainly due to smoking-related diseases. The research, published online by The Lancet medical journal, showed that severe obesity, measured as a BMI of between 40 to 50, while rare, was as dangerous for the body as smoking.

Dr Whitlock added: "In adult life, it may be easier to avoid substantial weight gain than to lose that weight once it has been gained. "By avoiding a further increase from a BMI of 28 to 32 a typical person in early middle age would gain about two years of life expectancy. "Alternatively, by avoiding an increase from a BMI of 24 to 32, a third above the apparent optimum, a young adult would on average gain about three extra years of life."

A person's BMI is calculated by dividing their weight in kilograms by their height in metres squared.


A bowl of porridge in the morning 'will make you feel fuller for longer'

I had porridge for breakfast for the first 16 years of my life and I certainly felt sustained by it. I was very slim then too!

Eating a bowl of porridge in the morning really will keep you feeling fuller for longer, scientists have discovered, in what could be the key to how the GI diet works. A new study suggests that foods with a low glycaemic index (GI), like oats, trigger the release of greater amounts of a hormone in the gut which delays hunger pangs by creating a "full" sensation. Scientists previously knew that a low GI diet took longer to digest, releasing sugar more slowly into the bloodstream.

Now a team of researchers have discovered that foods with a low GI score, which include brown bread and most fruit and vegetables, stimulate the release of around 20 per cent more of the GLP-1 hormone per meal than foods with a high GI ratio.

Dr Reza Norouzy, who led the study, said that the chemical was "one of the most potent hormones for suppressing appetite". She added:"Our results suggest that low GI meals lead to a feeling of fullness because of increased levels of GLP-1 in the bloodstream. "This is an exciting result which provides further clues about how our appetite is regulated, and offers an insight into how a low GI diet produces satiety."

The team, from King's College London, looked at the effects of different diets on 12 healthy volunteers. The results of their findings were presented at the annual Society for Endocrinology BES meeting in Harrogate. The GI score ranks carbohydrates according to the effect that they on the body's blood sugar levels.

Foods classed as having a low GI include granary bread, milk, most fruit and vegetables, while high GI foods include white bread, croissants and cornflakes.


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