The row about the relationship between sugary drink consumption and spiraling obesity took center stage at the American Dietetic Association (ADA) conference this week with two academics going head to head on one of the most controversial areas of nutrition science.
In the red corner was Dr Theresa Nicklas, professor at the Children's Nutrition Research Center at the Baylor College of Medicine, who pointed out that the percentage of energy derived from sugar sweetened beverages was steadily falling, which made it hard to argue that soft drinks were responsible for rising obesity rates.
She also claimed that evidence suggesting sugary drinks played a major role in obesity was inconclusive, with some studies suggesting a link and others not. She also noted that overweight and obese people frequently avoided full sugar drinks and that added sugar consumption could explain “virtually none of the variances in adolescents’ BMI scores”.
Meanwhile, there was “no evidence” that a soda tax would decrease obesity, and if prices went up on soda, consumers would probably just switch to fruit juice instead, she predicted.
Finally, singling out one nutrient or product group was not the way to address obesity, she argued. “If we’re going to tax soft drinks, why not tax pizza or donuts? We are righting the wrong battle here. We need a total diet approach.”
Liquid vs solid calories
In the blue corner stood Dr Barry Popkin, distinguished professor of nutrition at the University of North Carolina, Chapel Hill, who argued that calories from sugary drinks do not fill us up in the same way as solid foods, meaning people that consumed large volumes of soft drinks were at particular risk of taking in too many calories.
He added: “If we take in 200 calories in liquid, we won’t eat 200 fewer calories from foods [to compensate].”
While the difference between 'calories in and calories out' was what ultimately influenced weight gain or loss, the source and type of calories consumed did matter, with evidence suggesting that high consumption of refined carbohydrates increased risk factors for cardiovascular disease and metabolic health problems, he claimed.
“You can always say yes, we need more randomized controlled trials, but there comes a time when you have to take a stand… If we’d waited for all the evidence on tobacco to act we would still have been arguing about it in 2002.”
It was also important to look carefully at the source of funding for research in this field, he argued, with studies backed by beverage companies more likely to deliver ‘industry-friendly’ results, he claimed.
However, one audience member pointed out that the quality of the research - which could be independently assessed once it was published - should matter more than the funding source.
Another delegate also challenged Popkin’s empty calories hypothesis about liquid calories by pointing out that the first food humans consumed was a liquid (breast milk) which was uniquely satiating.
However, a third delegate took issue with Nicklas for appearing to support the ‘there are no bad foods, only bad diets’ argument, and prompted a round of applause in the auditorium by arguing that some foods were self-evidently healthier than others, making it perfectly reasonable to single out certain foods or beverages for criticism, especially if they contributed significantly to overall calorie consumption.