A new study has confirmed that being overweight or obese increases the risk of dying prematurely. However, it also found that this risk is around three times greater in men than in women.

The study involved data on 3.9 million adults who had taken part in 189 studies worldwide and it found that people who are overweight and obese have an increased risk of coronary heart disease, stroke, cancer and respiratory disease.

According to World Health Organization (WHO) estimates, some 1.3 billion adults around the world are overweight, while 600 million are obese. The prevalence of adult obesity in Europe is 20%, while in North America, it is 31%.

"On average, overweight people lose about one year of life expectancy, and moderately obese people lose about three years of life expectancy.

"We also found that men who were obese were at much higher risk of premature death than obese women. This is consistent with previous observations that obese men have greater insulin resistance, liver fat levels, and diabetes risk than women," explained the study's lead author, Dr Emanuele Di Angelantonio, of the University of Cambridge in the UK.

The study defined dying prematurely as dying between the ages of 35 and 69. This risk of premature death increased steadily as body mass index (BMI) increased, the researchers noted.

For example, if the risk of death before the age of 70 was 19% for men and 11% for women with a normal BMI, this would rise to 29% for men and 14% for women among the moderately obese. This is an increase of 10% for men and over 3% for women , i.e. the risk among men is three times as big.

Meanwhile, the researchers also estimated the reduction in deaths that would occur if a risk factor, i.e. excess weight, was eliminated. They said that assuming the links between high BMI and mortality are largely causal, if those who were overweight or obese were a healthy weight, this means that one in seven premature deaths in Europe could be avoided, and one in five in North America.

"Obesity is second only to smoking as a cause of premature death in Europe and North America. Smoking causes about a quarter of all premature deaths in Europe and in North America, and smokers can halve their risk of premature death by stopping. But, overweight and obesity now cause about one in seven of all premature deaths in Europe and one in five of all premature deaths in North America," explained the study's co-author, Prof Sir Richard Peto, of the University of Oxford.

The study also found a slightly increased risk of premature death among underweight people.

Details of these findings are published in the journal, The Lancet.

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