The obesity epidemic in the US may cut life expectancy, a study says.
One in three Americans are obese, experts say
Researchers said based on the current obesity levels life spans could fall by between four months and nine months.
If the rise in obesity - 50% a decade in both the 1980s and 1990s - was not stopped, the team said it could fall by two to five years within decades.
One in three Americans are now obese and the largest increases have been seen in children, the team led by the University of Illinois said.
The report, published in the New England Journal of Medicine, warned obesity could cut an individual's life expectancy by between five and 20 years as it increased the risk of dying early from heart disease, diabetes, cancer and kidney failure.
The average American has a life expectancy of 77.6 years after almost 200 years of continuous increases.
But report co-author David Ludwig said that could be about to change.
"The long-term consequences of the child obesity epidemic have yet to be seen.
"The tsunami of childhood obesity has not yet hit the shore - it takes many years for complications to develop.
"If the clock starts ticking at age 12 or 14, the consequences to public health are potentially disastrous - imagine heart attack or kidney failure becoming a relatively common condition of young adulthood."
A nine-month fall in life span would be greater than the negative effect of all deaths from accidents, murder and suicide, the report said.
But Samuel Preston, of the University of Pennsylvania, writing in an editorial for the journal, said the projections may be "excessively gloomy" because many Americans were beginning to wake up to the problem and adopt healthier lifestyles.
He added: "Obesity has clearly become a major personal and public health problem for Americans. It affects many aspects of our society."
Other areas of the world also have a growing obesity problem.
South African has similar levels of obesity as the US.
About 25% of the people living in the Middle East are obese or overweight, while obesity has risen by 100% among Japanese men since 1982.
In the UK, one in five people are obese and experts have warned the situation is getting worse.
The British government has proposed a series of measure to combat obesity, including restrictions on junk food advertising to children and a coding system to identify healthy food.