Does diet soda promote weight gain? Debate rages in the courts as Coca-Cola, PepsiCo, challenge ‘outlandish’ lawsuits
According to the plaintiffs: "Artificial sweeteners, including aspartame, appear to promote weight gain, and to trigger metabolic syndrome and diabetes," claims vigorously contested by the defendants, who argue that on a can of soda, the term 'Diet' simply means low calorie or reduced calorie, and that they are not making any weight management claims.
While most of the cases are still proceeding through the courts, one (Becerra v The Coca-Cola Company, 3:17-cv-05916) has recently been dismissed with leave to amend by Judge William Alsup, who found that Becerra’s claims were not preempted by federal law (as the soda giants had tried to argue), but that Becerra had failed to demonstrate that reasonable consumers were being misled.
To succeed in such a case, argued Judge Alsup, the plaintiffs would have to prove not just that there is a correlation between diet soda consumption and weight gain, but show evidence of causation.
This was hotly disputed by attorneys for the plaintiff in the case vs PepsiCo however, who argued in a March 14 letter to the judge overseeing their case that the “strong correlation between artificial sweeteners and weight gain” provided a plausible scientific basis for their consumer protection claims.
They added: “Even if Plaintiffs were required to prove that aspartame causes weight gain in order to be successful on the merits of her claims, they need not prove causation at the pleading stage.”
Soda giants: Correlation is not causation
PepsiCo’s attorney begged to differ, adding: “Judge Alsup dismissed the plaintiff’s complaint because he concluded that no reasonable consumer could be deceived that the word ‘diet’ in ‘Diet Coke’ could render the soft drink a weight loss product."
Branding the lawsuits 'outlandish,' Coca-Cola, in turn, said plaintiffs were trying to hold it accountable for weight management claims it was not making: "The ‘misleading’ message that Plaintiffs claim to have taken from the brand name—that the sheer act of drinking Diet Coke contributes to ‘healthy weight management’—can be found nowhere on Diet Coke’s label or advertising.”
Attorney: Cases look like a stretch
So what do legal experts think?
While the arguments made in the lawsuits are a “stretch,” according to Bruce Silverglade, principal at law firm Olsson Frank Weeda Terman Matz PC, the term 'diet' is nevertheless becoming more problematic in food marketing, said William Dance, attorney at law firm Tucker Ellis.
Speaking to FoodNavigator-USA when the cases were originally filed, he said: "Ultimately, it may be that plaintiffs’ position will be proven correct, and artificial sweeteners will go the way of trans fats, or at least someday FDA may no longer allow products made with artificial sweeteners to be labeled as 'diet' products. We may look back on Diet Coke, Diet Pepsi, and Diet Dr. Pepper as legacies of a simpler time when we wrongly believed that reducing calories by using 'diet' products would result in weight loss, or at least not in type 2 diabetes.
"But it is not clear that the studies plaintiffs rely on prove their position today."
'We may look back on Diet Coke, Diet Pepsi, and Diet Dr. Pepper as legacies of a simpler time'
He added: "Newer low-calorie drinks like Coke Zero, Pepsi Zero Sugar, and Dr. Pepper 10 escape this legal challenge because they are not [marketed as] 'diet' drinks. Their names simply state content (or lack of content) and leave it to consumers to draw their own conclusions about resulting health impacts.
"If these suits gain traction, finding content-based replacement terms for 'diet,' terms that cannot be viewed as asserting likely health outcomes, may be a solution for manufacturers."
*The cases are: Geffner et al v. The Coca-Cola Company, 1:17-cv-07952; Manuel et al v. Pepsi-Cola Company 1:17-cv-07955; and Excevarria et al v. Dr. Pepper Snapple Group Inc. et al 1:17-cv-07957; Becerra v. The Coca-Cola Co., No. 3:17-cv-05916.
In putative class action complaints - filed in New York last October vs Dr Pepper Snapple Group, The Coca Cola Company, and PepsiCo – plaintiffs argue that consumers might reasonably believe that zero-calorie sodas labeled as ‘diet’ “will assist in weight loss or management,” when in fact the opposite may be true.
Because the brain perceives the zero-cal beverages to be sweet, it effectively “misreads the number of calories present and reduces metabolism [because it thinks it’s about to get an energy boost], resulting in more calories being stored in the body,” alleged the plaintiffs, who are represented by law firms Derek Smith Law Group, The Law Office of Jack Fitzgerald, and Sacks Weston Diamond.
“In nature, sweetness signals energy. Generally, the greater the sweetness, the more calories that are available, so the human brain has evolved to expect the two to come together. When they do not, the brain can become confused, thinking there are fewer calories to burn. That is, artificial sweeteners, including aspartame, appear to promote weight gain, and to trigger metabolic syndrome and diabetes, because the brain misreads the number of calories present and reduces metabolism, resulting in more calories being stored in the body.”
Do high-intensity sweeteners promote weight gain?
The plaintiffs cite multiple studies in their complaint vs Coca-Cola [the complaints vs PepsiCo and Dr Pepper Snapple Group are near-identical and cite the same data], including a 2010 review by Brown et al indicating that “data from large, epidemiologic studies support the existence of an association between artificially-sweetened beverage consumption and weight gain in children.”
They also cite claims from Purdue University researcher Susan Swithers arguing that “frequent consumption of high-intensity sweeteners may have the counterintuitive effect of inducing metabolic derangements” and a 2008 study by Fowler et al alleging that “artificial sweetener use might be fueling--rather than fighting--our escalating obesity epidemic,” and noting that people who consumed the highest intakes of diet soda were more likely to be overweight or obese. (Critics of the research say that this simply shows a correlation - that people with a weight problem are more likely to reach for zero calorie beverages - not that the beverages cause their weight problems.)
The complaints also cite a 2014 study by Suez et al indicating that artificial sweeteners may induce glucose intolerance by altering the gut microbiota and a 2017 study by Huang et al arguing that artificial sweetener use has increased the risk of type two diabetes.
Industry-funded non-profit the Calorie Control Council, however, has been circulating a series of academic studies that counterbalance the research above, including a 2014 meta-analysis suggesting that “substituting low calorie sweetener options for their regular-calorie versions results in a modest weight loss and may be a useful dietary tool to improve compliance with weight loss or weight maintenance plans.”
The International Sweeteners Association, meanwhile, noted in July that "there is not a single published randomised controlled trial, the gold standard in nutrition research, that has shown that low calorie sweeteners use can lead to weight gain or any negative health effect."
Where do the major public health bodies stand on non-nutritive sweeteners?
In 2012, the American Heart Association and the American Diabetes Association issued a joint statement on the use of artificial sweeteners, saying “that when used judiciously, [artificial sweeteners] could facilitate reductions in added sugars intake.” The statement called for further research on non-nutritive sweeteners and cardiovascular risk but noted that “limiting added sugars is an important strategy for supporting optimal nutrition and healthy weights.”
The Academy of Nutrition and Dietetics, meanwhile, says that, “Consumers can safely enjoy a range of nutritive sweeteners and non-nutritive sweeteners when consumed within an eating plan that is guided by current federal nutrition recommendations."
According to the scientific report of the 2015 Dietary Guidelines Advisory Committee, “When low-calorie sweeteners are used to replace sugar, the resulting reduction in calories can help to achieve short-term weight loss."
But it added: "However, there is insufficient evidence (due to a paucity of data) to recommend the use of low-calorie sweeteners as a strategy for long-term weight loss and weight maintenance.
“Since the long-term effects of low-calorie sweeteners are still uncertain, those sweeteners should not be recommended for use as a primary replacement/substitute for added sugars in foods and beverages.”
A systematic review of animal and human studies published in the International Journal of Obesity in 2016 (click HERE) by Rogers et al concluded that, "Overall, the balance of evidence indicates that use of low energy sweeteners in place of sugar, in children and adults, leads to reduced energy intake and body weight."
