New research suggests obesity may shorten life by up to 10 years.

Dr James A Greenberg, a professor in health and nutrition at the City University of New York, found that mortality was likely to occur 9.44 years earlier among obese young and middle-aged Americans – those with a body mass index of higher than 30.

Among those with grade 1 obesity – a BMI of 30 to 35 - mortality was likely to occur 6.7 years earlier than non-obese, but among those with grade 2-3 obesity – a BMI of higher than 35 – this rose to 14.2 years.

Those classed as "overweight" were likely to die 4.4 years earlier.

The findings, published in the medical journal, Obesity, used data from 37,632 participants in three National Health and Nutrition Examination Surveys.

The estimates apply to non-smoking young and middle-aged adults without pre-existing serious illness.

"While obesity is a serious health problem, there are few reliable measures of its health hazards in the US," said Greenberg.

"My objective was to estimate how much earlier mortality is likely to occur for Americans who are overweight or obese, with the end goal of improving awareness of the impact that excess weight has on longevity."

"Experts agree the relationship between obesity and mortality is a complicated one," said Dr Harvey Grill, President of The Obesity Society. "However, it's clear from a vast body of research that obesity and mortality are associated, and that a higher BMI is tied to earlier death as well as higher rates of disease, many of which are serious."