The study pointed to evidence that the risk of death before an individual's 70th birthday grew "steadily and steeply" along with a broadening waistline.
The study, published in The Lancet, a leading UK medical journal, found that moderately overweight people lost about a year of life expectancy on average, but that mortality soared in those with more serious weight problems.
"On average, overweight people lose about one year of life expectancy, and moderately obese people lose about three years of life expectancy," said Emanuele Di Angelantonio from Britain's University of Cambridge.
"Severely obese people lose about 10 years of life expectancy."
The study used data from almost four million adults on four continents, which was sifted through by a large team of international researchers.
The information, described as the largest-ever pooled dataset on being overweight and mortality, was gathered from 239 large studies conducted between 1970 and 2015 in 32 countries in North America, Europe, Australasia, and southern and eastern Asia.
The team excluded current or former smokers, as well as those who had chronic diseases at the beginning of the studies.
Extra pounds worse for men
Another of the authors, Richard Peto of Oxford University, said that being obese was far more dangerous for men than it was for women. Obese men have higher fat levels and risk of diabetes than women with a similar Body Mass Index.
"The excess risk of premature death is about three times as big for a man who gets fat as for a woman who gets fat," Peto said.
A number of recent studies had indicated that obesity might not be as detrimental to life expectancy as previously thought, because of protective benefits that corpulent people enjoyed against certain diseases.
The World Health Organization (WHO) estimates that some 1.3 billion adults worldwide are overweight, while a further 600 million are obese. In Europe, the prevalence of adult obesity is 20 percent, while the amount rises to 31 percent in North America.
Earlier this year, the WHO warned that levels of child obesity were rising at an alarming rate, particularly in developing countries.
rc/bw (AP, AFP, Reuters)