If you love a sweet, fizzy soda but want to lose weight or reduce your sugar consumption, it seems logical to switch to the diet version.
Traditional soft drinks are a big contributor to America’s widespread obesity problem, according to most experts, and the nation’s sugar consumption is through the roof.
About 20 percent of Americans consume diet soda on a daily basis, and a little over half of them are consuming more than 16 ounces per day. A Centers for Disease Control and Prevention (CDC) report from 2012 also notes that the largest group of diet-drink consumers are higher-income individuals.
But diet drinks might not be healthier. Despite having a few benefits over sugary colas, diet soda is full of chemicals and artificial ingredients that some experts say cause plenty of harm. Read on for some common diet soda myths and the realities behind them.
Myth: Diet soda helps you lose weight
Last year, a widely publicized study out of the University of Colorado seemed to give credence to the notion that diet drinks can help you shed pounds. Published in the journal Obesity, it demonstrated that over 12 weeks, dieters who drank at least 24 ounces of diet soda lost more weight than those who drank at least 24 ounces of water, but no diet soda. That study, however, was funded by the American Beverage Association.
“I think that there was bias in the study,” says Dr. Ray Schilling, endocrinologist and author of “A Survivor’s Guide to Successful Aging.” On his blog, Ask Dr. Ray, he broke down the study and criticized its findings. “When you do not carefully control for all parameters— age, sex, history of diabetes, and so on— you find differences. The industry uses this type of cheating all the time to sell more product,” he says.
Most studies actually suggest that chronic consumption of diet soda is associated with weight gain or other related disorders like diabetes.
“There’s a lot of focus on using non-nutritive sweeteners like aspartame to lose weight,” says Sharon Fowler, who has a master’s degree in public health and is adjunct assistant professor at the University of Texas Health Science Center at San Antonio.
Fowler was the lead author on another study that linked diet soda to increased belly fat and metabolic syndrome. The study, which was published in March in the Journal of the American Geriatrics Society, found that as diet soda consumption increased, so did waist circumference in adults over 65, though weight gain was more stable.
“There was almost a quadrupling in [increase in] waist circumference in daily drinkers compared to non-diet soda drinkers,” Fowler says. She notes that increased fat around the midsection is linked to serious medical problems down the road, much more so than excess fat in the lower body.
Fowler’s study was comprehensive but correlational, meaning that it only established a link between diet soda and belly fat, not a verified mechanism. When asked to speculate about why diet soda may cause increased waist circumference and metabolic syndrome, she said she believes non-nutritive sweeteners change the way the body regulates sugar. One study Fowler pointed to established that people who consume large amounts of artificial sweeteners can become glucose-intolerant in just a week.
Myth: Diet soda definitely causes cancer
This myth comes from a study about aspartame, the main sweetener in diet soft drinks. In that study, which was done on rats, researchers linked aspartame consumption to brain cancer, leukemia and lymphomas. Italian researchers overfed 1,900 rats aspartame at a rate and concentration no human would likely consume.
While there was a link found between aspartame dosage and cancer, it would be next to impossible for a human to consume a similar ratio of aspartame. For that reason, the study has been largely criticized by other researchers, and a large human study found no increased risk of cancer in humans. No studies have confirmed a link between aspartame or diet soda and cancer in humans. That doesn’t mean that a link won’t be found in the future, but it hasn’t been firmly established yet.
Myth: With no calories or added sugars, diet soda is harmless
“People who drink diet soda tend to think they’re in a risk-free environment because there are no calories,” Fowler says, “but diet soda is very acidic, much more so than regular soda.” Too much acid in the diet can lead to acid reflux diseases, esophageal hernias, and tooth decay.
She believes all that acid also disrupts the balance of microorganisms in the gut. “Our intestines are their own ecosystem, like a rain forest,” she explains. “It’s very complex, very delicate, and it all works together.” But constantly drinking diet soda is like an acid rainstorm to that rain forest. Containing no nutrients, the acid can destroy many kinds of gut flora. Plus, it tends to replace water in heavy drinkers’ diets, leading to low-grade dehydration.
An occasional diet soda is fine, but like anything sweet, diet drinks should still be consumed in moderation. If you’re a daily diet soda drinker, opt for 12-ounce cans instead of 20-ounce bottles. Alternatively, replace a few diet sodas per week with tea or water to reduce your consumption.