Being obese has long been considered unhealthy, but two new medical studies equate obesity with lost years of life.
U.S. and Dutch researchers report independently of each other that obesity signficantly shortens life span, and they offer numbers of lost years to support this observation.
The U.S. study by investigators at the University of Alabama and Johns Hopkins University examined years of national government health survey data on tens of thousands of people. "We were looking into the extent to which obesity would affect years of life lost," said researcher David Allison of the University of Alabama. "That is, how much longer would one live if one maintained a low to moderate body weight versus an overweight or obese body weight?"
The data in the Journal of the American Medical Association show that severely obese people can expect their lives to be shortened by up to 20 years, especially if they are around 20 years old.
A severely obese young black American woman can expect to lose four or five years of life, and a severely obese white woman, five to eight years. It gets worse for men, ranging from 12 fewer years of life for a young white male who is very obese to 20 fewer years for a young black man in the same condition.
"To see that years of life lost could be on the order of 12 to 20 years is quite astounding. Their severe obesity puts them at much greater risk for earlier death, and the number of years of life they're likely to be losing is great," Mr. Allison said.
The Dutch study in another U.S. journal, the Annals of Internal Medicine, makes the same point with data from 3,300 people tracked in the 55-year-old Framingham, Massachusetts, Heart Study. It finds that, on average, adults who were obese at age 40 lived six to seven years less than their normal weight counterparts. Smoking made things worse. Obese smokers at age 40 lived 13 to 14 fewer years.
The authors of the study say that because of the increasing prevalance of obesity in industrial countries, better prevention and treatment should become high public health priorities.
In Birmingham, Alabama, David Allison hopes his study will motivate fat people to lose weight. "If they can think in terms of how many more years they would live if they were thin or normal weight versus obese, that may have more impact on them," he said.