In a new study, researchers found that the current obesity rates in adults in the United States could be the result of dietary changes that took place decades ago.
The research was conducted by a team at the University of Tennessee, Knoxville.
Consumption of excess sugar, particularly in sugar-sweetened beverages, is a known contributor to both childhood and adult obesity.
Many population health studies have identified sugar as a major factor in the obesity epidemic.
One problem with this theory, however, has been that sugar consumption in the US began to decline in the late 1990s while obesity rates continued to rise well into the 2010s.
That increase shows in the numbers: By 2016, nearly 40 percent of all adults in the US—a little over 93 million people—were affected by obesity.
In Tennessee alone, the adult obesity rate more than tripled, from about 11 percent in 1990 to almost 35 percent in 2016. By 2017, however, obesity in Tennessee had fallen 2 percent from the previous year.
If high-sugar diets in childhood have long-lasting effects, the changes we see now in adult obesity rates may have started with diets decades ago, when those adults were children.
The team says that since the 1970s, many available infant foods have been extremely high in sugar.
Other independent studies in medicine and nutrition have suggested that sugar consumption during pregnancy can cause an increase in fat cells in children.
Up to this point, no studies had explicitly explored the temporal delay between increased sugar consumption and rising obesity rates.
To address the problem, the authors modeled the increase in US adult obesity since the 1990s as a legacy of the increased excess sugar consumption measured among children in the 1970s and 1980s.
They tested their model using national obesity data collected between 2004 and 1990 by the Centers for Disease Control and Prevention.
They compared those obesity rates with annual sugar consumption since 1970 using the median per capita rates issued by the US Department of Agriculture.
The model also roughly captures how obesity rates vary by age group among children and teenagers.
Their results suggest that the dietary habits learned by children 30 or 40 years ago could explain the adult obesity crisis that emerged years later.
A large portion of the sugar increase before 2000 was from high fructose corn syrup (HFCS), which after 1970 quickly become the main sweetener in soft drinks and a common ingredient in processed foods.
At peak sugar consumption, in 1999, each person in the US consumed on average around 60 pounds of HFCS per year and more than 400 calories per day in total excess sugars.
The researchers are planning to continue their studies in the area by exploring the effect of sugar-sweetened beverages.
The lead author of the study is Alex Bentley, head of UT’s Department of Anthropology.
The study is published in Economics and Human Biology.
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