While the association between low income and obesity has been previously established, new evidence indicates that this relationship is only about three decades old.
The study, published in Palgrave Communications, was conducted by researchers at the University of Tennessee (UT).
“We found that the relationship between low income and high rates of adult obesity in the U.S. is not observable until the early 1990s,” said coauthor Alex Bentley, head of UT’s anthropology department. “As recently as 1990, this was not a detectable problem.”
A correlation between #obesity and income has only developed in the past 30 years https://t.co/IBCs4dvOyD pic.twitter.com/im72oO001j
— Neil Floch MD (@NeilFlochMD) December 12, 2018
Researchers obtained country-level data from the Centers for Disease Control and Prevention (CDC) for 2004–2015. Older state-level data, going back to 1990, were derived from annual reports for the Trust for American’s Health and the Robert Wood Johnson Foundation. They used U.S. Census data to compare obesity rates to median income.
In earlier years, there was no connection between obesity and income, the researchers discovered.
There is a strong negative correlation between household income and both obesity and diabetes. This negative correlation, however, has only developed in the past 30 years, according to a study in the journal @PalCommsOA. https://t.co/VAYXPuOmpu
— Springer Nature (@SpringerNature) December 11, 2018
“We find the reverse gradient has only existed for less than thirty years,” they wrote. “In the U.S. in 1990, when population–scale obesity rates were about a third of what they are today, there was no correlation between income and obesity or diabetes.” These associations have only become apparent over the past 30 years—most notably in the past few years.
The USA breaks with thousands of years of history: poor people are now more obese than rich people. But, for the first time, we show that this 'negative correlation' only emerged in the last 30 years. New paper from myself, @ralexbentley and @OrmerodPaul.https://t.co/312lRZJzhQ
— Damian Ruck (@damianjruck) December 11, 2018
“By 2015, the correlation was stronger than ever: in states where median household incomes were below $45,000 per year, like Alabama, Mississippi and West Virginia, over 35% of the population was obese, whereas obesity was less than 25% of state populations where median incomes were above $65,000, such as in Colorado, Massachusetts or California,” the study authors wrote.
The researchers theorized that the increased use of high fructose corn syrup in highly processed foods in recent years may be a factor—an idea the researchers are still exploring.
Our new study: https://t.co/lEVvz07AcH
— Alex Bentley (@ralexbentley) December 11, 2018
“We’re now investigating the effect of processed sugars on generations who were entering adulthood by 1990, when high obesity rates began to correlate with low household incomes,” Bentley said.
In their conclusion the researchers wrote, “A fuller explanation of the timing and geography of the obesity epidemic will require the specific history of societal–level factors. Besides the suggestive temporal concurrence between obesity, food deserts and HFCS–sweetened beverages, additional clues lie in the considerable variation in the strength and evolution of the reverse gradient within different states of the U.S.”
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Sources: Palgrave Communications, The University of Tennessee
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