For years, the U.S. Dietary Guidelines urged Americans to drink less sugary beverages. And for years, many Americans listened.
But after a decade of falling consumption, rates have stalled at well above the recommended limit, according to statistics released Thursday by the Centers for Disease Control and Prevention.
The agency found that adults and children are both consuming roughly the same number of calories from soda, sports drinks and other sugary beverages now as they did in 2009-2010, the last time the CDC published comparable data.
"The amount of sugar that children in particular consume is still astounding," said Rachel Johnson, a professor of nutrition at the University of Vermont and a spokeswoman for the American Heart Association. "We recommend that children drink soda once a week or less. We're seeing that two-thirds drink it on a daily basis."
The CDC numbers counter the perception that Americans are continuing to shirk sugary drinks and embracing a healthier lifestyle out of a desire to avoid the risks of obesity and diabetes. Researchers don't exactly know why the leveling off has occurred, but there are several potential explanations. One is that while soda sales are down, Americans may be turning in growing numbers to teas, flavored waters and other energy drinks with plenty of sugar added.
According to the market research firm Euromonitor, the U.S. market for conventional carbonated sodas contracted .6 percent between 2011 and 2016. During that same period, sales of energy drinks, sports drinks and iced teas and bottled coffees grew by between 5 and 13 percent.
Meanwhile, it's also possible that the initial decline in sugary-beverage consumption came among Americans who were particularly receptive to changing their behavior, such as upper-income individuals. That leaves a soda-drinking population whose habits are changing more slowly.
"My guess is that we might be seeing different trends by age and socioeconomic status," said Walter Willett, a professor of epidemiology and nutrition at Harvard's T.H. Chan School of Public Health. "People with higher levels of education and income have made dramatic changes to their diets overall in recent years. Many people with lower levels of education and income have seen no improvement."
Sugary beverages have been linked directly to obesity, diabetes and heart disease, which is why public health agencies have gone to great lengths to discourage their consumption. The plateauing may raise questions about whether public health efforts are working or whether new ones are needed.
In 1999-2000, the average adult drank 196 calories' worth of sweetened beverages per day. By 2009-2010, that number had fallen to 151. In the period from 2011-2014, it fell only a few calories further, to 145. The pattern is similar among children, who drank 223 calories of soda and other drinks in 1999 and 155 calories in 2009. The number has stuck at 143 since then, which represents 7.3 percent of a child's calorie intake, on average. The latest declines were not considered statistically significant.
"If you extrapolate our findings out, that means 111 million adults and 147 million kids still drink at least some sugar-sweetened beverage daily," said Asher Rosinger, an epidemiologist at the CDC and the lead author of the research.
In line with other studies, the new CDC analysis found large disparities between men and women as well as between different ethnic groups: Men generally drink more soda than women; blacks, whites and Hispanics drink more than twice the soda that Asian Americans do.
There are differences by age and generation, as well, said Dariush Mozaffarian, dean of the Friedman School of Nutrition Science and Policy at Tufts University. Mozaffarian believes that the average soda consumption may actually tick up again as Generations X and Y age into their 60s.
Generally speaking, soda consumption increases throughout a person's adolescence, peaking in early adulthood and falling off from there. For children, those changes are the result of age: You wouldn't give a 2-year-old a Coke, probably. But for adults, Mozaffarian said, the fluctuations are generational: Today's seniors don't drink as much soda because they didn't drink much soda growing up. Tomorrow's seniors may well be different.
"That is really worrisome," Mozaffarian said. "We need to have a culture change around soda, the same way we had a culture change around drunk driving, smoking, bike helmets for kids, car seats and seat belts."
For advocates, such a culture shift is urgent - particularly given growing evidence of soda's unique public health harms. Excess sugar can contribute to obesity and other problems in any form, but it's particularly troublesome in beverages, Johnson said, because most people don't realize how much they've had.
Sugary drinks have been linked to obesity in children and adults. It also contributes to heart disease, type II diabetes and some obesity-related cancers, all of which have reached epidemic proportions in the United States.
To address some of these harms, the Dietary Guidelines explicitly recommend that all added sugars account for no more than 10 percent of the calories in an individual's diet. The American Heart Association goes even further, recommending that children get no more than 100 calories a day from sugary beverages. But according to the CDC data, roughly 20 percent of kids drink two sodas a day, and roughly 10 percent drink three or more.
"We protect them from alcohol, tobacco (and) guns," Willett said, "but not Big Soda, which is extremely insidious and cares nothing about the carnage it causes."
Willett and others argue that new policies are needed to keep soda consumption trending down - policies on the order of the Smart Snack rules, which have taken sugary drinks out of schools, and the forthcoming updated Nutrition Facts Label, which will highlight the sugars added during processing to such drinks as juice cocktails.
They'd also like to see the beverage industry agree to stop marketing to children, something many processed food purveyors have already done. And they'd like to see more cities pass soda taxes: In Berkeley, where the first U.S. soda tax was approved, researchers have found that in the past three years, consumption is down by as much as 20 percent .
Unfortunately, Willett points out, most Americans don't live in a place like Berkeley — and efforts to further reduce sugary drink consumption rely on reaching them. That makes education and awareness all the more important.
"We all know we're in this for the long term," Willett said. "We're making progress — but you can't take your eyes off it for a minute."