When it comes to Americans’ widening waistlines, the next 2 decades may serve up a side order of good news – and a heaping helping of bad news.
The good news: The rate of increase in the number of obese Americans may level off by 2030, leading to a lower prevalence of obesity than previously estimated.
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The numbers aren't guaranteed, but by 2030 the United States is projected to see a 33% increase in obesity.
The bad news: The number of obese Americans will still climb by a third in that period, while the nation’s tally of superobese – those who are more than 80 pounds overweight – will more than double.
The result: The cost to the nation from obesity-related morbidity and mortality will be massive, according to Eric Finkelstein, Ph.D., lead author of a study published online May 7 in the American Journal of Preventive Medicine.
By 2030, the United States will see a 33% increase in the prevalence of obesity and a 130% increase in the prevalence of severe obesity, predicted Dr. Finkelstein of the Duke Global Health Institute, Durham, N.C., and deputy director of the Health Services Research Program at Duke-NUS Graduate Medical School in Singapore, and his associates.
Previous studies had suggested that 51% of the U.S. population would be considered obese by that decade. But the model created by Dr. Finkelstein and his colleagues at Duke and the Centers for Disease Control and Prevention puts the U.S. obesity rate at 42% by 2030.
A total of 11% of the nation will be considered severely obese, compared with 5% now, Dr. Finkelstein predicted at a press briefing.
Those numbers aren’t carved in stone, however.
Dr. Finkelstein called his paper’s numbers "reasonable estimates as to what the future will hold," but he added that "predicting obesity is tricky."
To create their predictive model, the researchers used data from the Behavioral Risk Factor Surveillance System (BRFSS) covering the years 1990-2008.
They added variables that might affect the rate of obesity, including unemployment rates; prices for alcohol, gas, and fast food; prices of groceries relative to non–grocery items; prices of healthier foods relative to less-healthy foods; access to the Internet; and the number of fast-food and full-service restaurants/10,000 people. Those data were drawn from the U.S. Bureau of Labor Statistics, the American Chamber of Commerce Research Association, and the Census of Retail Trade.
The analysis showed that no single variable was the cause of obesity, said Dr. Finkelstein. In fact, the study’s variables probably only explain about 5% of obesity he added. Other studies have suggested that as much as 70% of obesity is genetically determined.
The investigators noted several limitations to their predictive model, including the fact that it assumes the variables used will remain constant. In addition, the BRFSS relies on self-reported height and weight. The researchers attempted to counter that by adjusting for potential underreporting.
Getting at obesity’s causes now could help lower obesity rates later, the researchers said.
Childhood obesity may be a major risk factor for obesity later in life, noted Dr. Finkelstein and coauthor Dr. William Dietz. A child’s school environment has been shown to play a predominant role in pediatric obesity, added Dr. Finkelstein.
"Keeping obesity rates level could yield a savings of nearly $550 billion in medical expenditures over the next 2 decades," Dr. Finkelstein said in a statement.
Bending the obesity curve slightly downward would deliver more benefits.
"Even a 1% decrease from the predicted trend would lead to 2.6 million fewer obese adults in 2020 and 2.9 million fewer obese adults in 2030," the study’s authors explained.
The study’s authors reported no conflicts of interest.