gWhile rowing, Olivia Dreizen Howell, 39, was “living” on diet soda. So is his family. At a family reunion in 1996, everyone wore T-shirts with their shared last name in Diet Coke-can font. “We drank Diet Coke, Diet ginger ale, and Diet Sprite like water; there was no difference in our house,” she says.
Like many people, Howell believed that unsweetened soda was a good choice. But recent research casts doubt on this assumption, linking diet drinks to mood disorders, the development of fatty liver, autoimmune diseases and cancer.
Before you pour your diet soda down the drain (a step actually recommended by a health professional), know this about diet soda studies: the vast majority of them are observational; drawn from public health records and long-term population data. as opposed to the scientific gold standard of double-blind, placebo-controlled studies.
Here’s what we know so far about what diet soda can do to your health.
Diet soda is linked to a higher risk of diabetes
“Type 2 diabetes seems to be the strongest link” when it comes to diet soda and its health risks, says Susan E. Swithers, a professor of neuroscience at Purdue University who studies the effects of diet soda on metabolic health. “A consistent finding.” A 2023 study of nearly 106,000 people found that people who consumed more artificial sweeteners had a higher risk of Type 2 diabetes than people who did not eat or drink any.
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Swithers’ previous studies found that people who drink a lot of diet soda face increased risks for excess weight gain, Type 2 diabetes, cardiovascular disease, and metabolic syndrome, a set of conditions involving excess body fat (especially in the middle). Northwell Health endocrinologist Dr. Blood sugar, blood pressure and high triglycerides “all pose risks for the development of Type 2 diabetes and heart disease,” says Barry Schuval.
Linked to worse heart health
Many studies have found that artificially sweetened beverages like diet soda are linked to heart problems, specifically increased risks of stroke, coronary heart disease, and heart attack. A recent March 2024 study found that people who drank more than two liters of artificially sweetened beverages per week had a 20% higher risk of atrial fibrillation than people who did not consume sweetened beverages. “It’s important not to assume it’s low-calorie [diet drinks] We are naturally healthy,” says lead author and professor of endocrinology and metabolism at Shanghai Ninth People’s Hospital in China. NingjianWang.
Melissa Prest, a dietitian and spokesperson for the Academy of Nutrition and Dietetics (who was not involved in the study), emphasized that the observational nature of the study means we don’t know why this link occurs. Before drawing any conclusions about whether diet drinks increase the risk of atrial fibrillation, we need more research “to understand all the potential variables such as health conditions, body weight, physical activity and other dietary habits,” Prest says.
Diet soda linked to cancer
In July 2023, after reviewing human and animal studies, the World Health Organization (WHO) added aspartame, a common ingredient in diet soda, to its list of ingredients “likely to be carcinogenic in humans.” This may sound worse in theory than it does in practice: The World Health Organization has concluded that a person weighing about 150 pounds can safely drink about eight cans of aspartame-sweetened diet soda a day.
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Schuval says that even with this definition, aspartame is not necessarily carcinogenic. “We have to keep in mind that correlation does not necessarily mean causation,” he says, and the current research is inconclusive.
Other studies have found potential links from diet soda to cancers including colon, uterine, kidney and pancreatic. But weight gain, rather than diet soda, may be the culprit, Schuval says.
Diet soda linked to weight gain
Artificial sweeteners such as aspartame, sucralose, and saccharin are much sweeter than sugar and can alter the sweet taste receptors in your body. Some experts think this may cause changes in your body’s hunger and satiety hormones, causing you to eat and drink more than you normally do. But the theory is not a slam dunk. “While this change has been widely reported in animal studies, inconsistent results have been obtained in human-based studies,” says Prest.
Another possibility is that both sugars and artificial sweeteners can disrupt the healthy balance of gut bacteria in the gastrointestinal tract, leading to the development of insulin resistance and Type 2 diabetes, Prest says. This, too, is difficult to prove in studies, says Leah Reitmayer, a dietitian in Sanford, N.C., and those that point to this path are often small and inconclusive.
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As with many nutrition studies, associations found between diet soda and weight gain (and obesity) can be misleading. “Research shows that more obese individuals drink more diet soda than usual, but also eat more than healthy-weight adults,” says Reitmayer. More research is needed to determine whether diet soda causes people to gain weight or whether the relationship is complicated by other factors.
What to make of all this research?
Overall, the findings are mixed, leading to confusion among consumers about whether diet soda is a safe beverage.
Swithers believes we still have more questions than answers. While he says he’s convinced there’s a real link between diet soda and Type 2 diabetes, the evidence that artificial sweeteners contribute to cancer and heart disease is less clear. “It depends on what explains this relationship,” Swithers says. Are people who choose to drink diet soda already at higher risk for certain health problems? Are all artificial sweeteners the same? Is there another variable that scientists haven’t looked at?
“This is where it gets really muddy,” he says. Unfortunately, we’ll have to wait to get a more comprehensive picture of diet soda’s health effects.
Is diet soda at least better for you than regular soda?
If you regularly drink sugary soda, all experts recommend switching to water (naturally). But other than that, many people prefer you to drink diet. “Some people find that artificially sweetened beverages help them control their blood sugar better,” says Prest.
Another reason is that we have much more convincing evidence about the harms of excess sugar than artificial sweeteners. Research over the years has linked sugar to conditions such as obesity, inflammation, heart disease, metabolic syndrome, insulin resistance, worsening Type 2 diabetes or prediabetes, weight gain, and tooth decay, and some studies have even shown that reducing added sugar in foods is essential. The U.S. food supply could save money and lives.
It’s also important to consider what else could replace your diet soda. Dan DeBaun, a 32-year-old public relations manager who lives in Minnetonka, Minnesota, uses diet soda as a tool to cut down on alcohol. “I’ve never drank a lot of alcohol before, but after more studies emerged about its negative health effects, I wanted to cut back further,” she says. After a successful “dry October” in which he abstained from alcohol entirely, he realized that he still enjoyed having a drink when he was out with friends or at a sporting event or concert. So he would order Diet Coke or Diet Pepsi.
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“Drinking diet soda doesn’t make me feel great, but compared to alcoholic beverages, I think it’s a net positive,” says DeBaun. “I used to only drink one, but I found that drinking it was a good alternative.”
And, dentally speaking, diet soda is clearly superior to regular. “One benefit of artificial sugars is their role in reducing tooth decay,” says Prest. “When sugar-sweetened beverages are replaced with artificially sweetened beverages, the risk of tooth decay or cavities is reduced,” he says, and this is due to a reduction in the growth of the bacteria that cause them.
How to limit your diet soda intake or quit it altogether
Few among us can give up our strict diet-soda habit (cold turkey), says Swithers, but there’s still plenty you can do to cut back.
Make it cum (for real)
People often think they need more food or drink to feel satisfied than they actually do. If you’re craving diet soda, open a can or bottle, take a few sips, and pour the rest down the sink. After just a few sips you may find your desire satisfied. “Pausing after some drinking to consider whether you want more soda can be a helpful step to reduce consumption,” says Swithers.
Treat your diet soda like candy
Instead of thinking of your diet soda as a beverage, Swithers suggests thinking of it as a candy. Eating with food this way can start to seem ridiculous. “Most adults wouldn’t open a bag of candy and spill it on their dinner plate,” he says. “Just because it’s in a glass doesn’t make it magical in any way. Would you put a bag of jelly beans as a garnish with your meal?”
Hide your water
Many people drink diet soda because they don’t like the taste of water. To add an appealing flavor to a glass of water, add some frozen fruit (especially juice-yielding types like pineapple, strawberries and mango). Using seltzer instead of still water will make it taste more like the sparkling treats you love.