People who are obese are at increased risk of heart disease

Delegates will also discuss the increasing strain the condition is putting on health services.

Obesity is estimated to cause 70,000 new cancer cases in Europe every year and also increases the risk of heart disease, strokes and diabetes.

The conference will pay particular attention to overweight children.

In some countries, including Italy, nearly 40% are obese, whereas the figure is lower in northern Europe.

Fat 'biologically active'

The UK, Hungary, Romania, Greece and Albania have the highest proportions of obese adults and this is putting increasing strain on healthcare.

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People who are overweight or obese are at increased risk of heart disease, stroke, diabetes, osteoarthritis and even depression.

BBC health reporter Ania Lichtarowicz says research shows that fat is biologically extremely active - producing hormones and other chemicals - and it is these that may be causing cancer.

Until doctors know exactly why being fat is so bad for us the only solution to the obesity epidemic will be to encourage healthier living, she adds.

New guidelines

The conference comes days after the World Health Organisation adopted an unprecedented policy on diet and health to tackle a global increase in obesity.

The voluntary plan was hammered out at talks in Geneva in the face of stiff opposition from lobbies such as the sugar-producing nations.

It includes guidelines for urban planners on encouraging exercise as well as advice on healthy eating.

Nearly one in six people worldwide is now considered overweight.