Researchers have vastly underestimated the number of deaths caused by obesity in the United States, a new report reveals.
Obesity accounts for 18% of deaths among black and white Americans between the ages of 40 and 85, according to a study published online Aug. 15 in the American Journal of Public Health. Previous estimates had placed obesity-related deaths at only 5% of all US mortalities.
"This was more than a tripling of the previous estimate," said study author Ryan Masters, who conducted the research as a Robert Wood Johnson Foundation scholar at Columbia University's Mailman School of Public Health, in New York City. "Obesity has dramatically worse health consequences than some recent reports have led us to believe."
Earlier estimates erred by overlooking generational differences in the way the obesity epidemic has affected Americans, Masters said.
Because younger generations have been exposed longer to risk factors for obesity, they are at even greater risk of becoming overweight or obese and suffering all the health problems that accompany the extra pounds, the researchers warned.
"A 5-year-old growing up today is living in an environment where obesity is much more the norm than was the case for a 5-year-old a generation or two ago. Drink sizes are bigger, clothes are bigger and greater numbers of a child's peers are obese," study co-author Bruce Link, a professor of epidemiology and sociomedical sciences at Columbia, said in a statement. "And once someone is obese, it is very difficult to undo. So, it stands to reason that we won't see the worst of the epidemic until the current generation of children grows old."
The researchers investigated this possibility by breaking the population down into "cohorts", or generations, and studying the effect of obesity on deaths for those age groups.
Using these generational groups, they analysed 19 years' worth of annual US National Health Interview Surveys from 1986 through 2004 and compared those findings to individual mortality records from the National Death Index. They focused on ages 40 to 85 to exclude deaths caused by accidents, homicides and congenital conditions, the leading causes of mortality for younger people.
"Successive cohorts are living in this new environment and are at greater risk of obesity at earlier times in their lives," Masters said. "Each specific cohort looks like a wave that's grown bigger than the cohort that has come before it."
For example, Masters and his colleagues noted obesity's increasing effect on mortality in white men who died between the ages of 65 and 70 in the years 1986 to 2006.
Obesity accounted for about 3.5% of deaths for those born between 1915 and 1919, but it accounted for about 5% of deaths for those born 10 years later. Obesity killed off around 7% of those born another 10 years later.
Women appear to be more vulnerable than men to dying from obesity. Black women had the overall highest risk of dying from obesity or being overweight at 27%, followed by white women at 21%.
Dr. Georges Benjamin, executive director of the American Public Health Association, said the new research provides a helpful framework for understanding and tackling the obesity epidemic.
"Up to now, it's been a unilateral discussion about how obese you were or how much body fat you had," Benjamin said. "The solutions are not only more exercise and eating better, but a whole range of environmental factors we're going to have to address. The generation we have now is expected to be obese longer. That's a core reason we need to change things now if we're going to make this a healthier generation."
To that end, the study does validate current efforts by public health officials to combat the obesity epidemic by focusing on youngsters, Masters said.
"The fact they've been trying to stave off obesity earlier and earlier in life, I think, is the right thing," Masters said. "It's a reaffirmation of the public health campaigns that are putting obesity at the forefront."
For more about obesity, visit the US National Library of Medicine.