The data reveals a sharp increase among adults from just over a decade ago, when the obesity rate was less than 34 percent. Experts are especially concerned that attempts to raise awareness about bad eating habits and poor diet haven't been able to curb the trend.
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"Most people know that being overweight or obese is unhealthy, and if you eat too much that contributes to being overweight," Dr. James Krieger, clinical professor of medicine at the University of Washington and executive director of Healthy Food America, an advocacy group, told The New York Times. "But just telling people there's a problem doesn't solve it."
Among adult women, the obesity rate has slightly passed 40 percent, whereas among men, it hovers around 38 percent. Severe obesity (defined as a body mass index of 40 or more) is also on the rise across the adult population, increasing by 2 percent and reaching 7.7 percent overall. Before 2007, severely obese adults made up about 5.7 percent of the population.
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When it comes to youth, the rate of obesity increased only slightly, rising from 16.8 percent in 2007-2008 to 18.5 percent in 2015-2016. However, Dr. Craig Hales, co-author of the survey research, said this small rise "could be due to sampling error."
A more startling increase was also observed among children ages two to five. The rate of obesity among this demographic increased from 10.1 percent before 2007, to 13.9 percent in 2016.
Although the data reveals that Americans are getting fatter overall, it doesn't outline clear causes. Nutritionists point to the usual suspects: sedentary lifestyles, genetics, and of course, poor diets. Euromonitor International reports that fast food sales rose by 22.7 percent in the U.S. between 2012 and 2017. Packaged food sales also increased by 8.8 percent.
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According to the Harvard T.H. Chan School of Public Health, "the typical Western diet" is a major cause driving obesity.
"Large meals high in refined grains, red meat, unhealthy fats, and sugary drinks play one of the largest roles in obesity," the school's website states. "Foods that are lacking in the Western diet – whole grains, vegetables, fruits, and nuts – seem to help with weight control, and also help prevent chronic disease."
The school argues that the government should promote policies and environmental changes "that make healthy foods more accessible and decrease the availability and marketing of unhealthful foods." Although such initiatives have moved forward in the past decade, experts believe more needs to be done.
As the obesity epidemic continues to grow, doctors warn that we cannot simply accept this reality as the new normal, ABC News reported. If we accept obesity as a fact of American life, doctors say we will also have to accept higher premature death rates.
Read the full study at jamanetwork.com.