Soft drinks, including diet versions, have been linked to obesity, diabetes and heart disease in dozens of studies. But what's in Diet Coke that's bad for you? After all, this beverage has no calories or sugars.
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As it turns out, diet soda might be just as harmful as sugary drinks. Although it doesn't directly cause weight gain, it increases sugar cravings and affects your metabolism.
Diet Coke Nutrition Facts
About one-fifth of Americans drink diet soda on any given day, according to the Centers for Disease Control and Prevention. Diet coke, for instance, has been around for decades and enjoys popularity worldwide. It's the go-to choice for millions of gym-goers and healthy eaters.
Surprisingly, health organizations warn about the dangers of diet soda. For example, a May 2018 cohort study published in Current Development in Nutrition states that artificially-sweetened beverages cannot be ruled out as an independent risk factor for diabetes. Furthermore, it doesn't protect against type 2 diabetes, as it was once thought.
So, what's in Diet Coke that's bad for you? One can (12 fluid ounces) has zero calories, zero sugar, zero fats and negligible amounts of sodium. Diet Coke calories are not a reason for concern. Its ingredients, on the other hand, may pose health risks. These include:
- Carbonated water
- Caramel color
- Potassium benzoate
- Phosphoric acid
- Citric acid
- Natural flavors
Aspartame, the sugar substitute in Diet Coke, contains phenylalanine, an amino acid that may cause seizures and brain damage in people with phenylketonuria, a genetic disorder. The Mayo Clinic warns that aspartame should also be used with caution by individuals with anxiety disorders, sleep problems or tardive dyskinesia. When consumed in excess, this additive may worsen anxiety and cause jitters.
Diet Coke and Weight Loss
Diet coke might not be as diet-friendly as you think, according to a research paper featured in the journal Trends in Endocrinology and Metabolism in September 2013. Artificially-sweetened beverages (ASB) have been linked to obesity, type 2 diabetes, metabolic syndrome, high blood pressure and cardiovascular disease.
The relationship between ASB and weight is controversial, though. For every study showing that diet soda contributes to obesity, there's another that states the opposite.
Researchers agree that ASB consumers often end up eating more because of the initial "calorie saving" effect, as noted in a review published in the August 2012 edition of Diabetes Care. The journal Trends in Endocrinology and Metabolism reports similar findings. Several studies suggest that diet soda may increase appetite and sugar cravings, but further investigation is needed to confirm these claims. These potential side effects are largely due to artificial sweeteners.
Furthermore, a recent cohort study conducted on children has found that those who consumed low‐calorie sweetened beverages ate an extra 196 calories per day. The results were published in the May 2019 issue of the journal Pediatric Obesity. According to the Diabetes Care review, diet soda may facilitate weight loss as long as there isn't a compensatory increase in calorie intake from other sources.
Does Aspartame Increase Blood Sugar?
Diet Coke is also a popular choice among people with diabetes. Since it's sugar-free, it shouldn't raise blood glucose levels. Again, most studies are conflicting.
A study cited in Trends in Endocrinology and Metabolism points out that diabetes risk may increase in those who consume one or more artificially-sweetened or sugar-sweetened beverages per day. Another study, which was published in the American Journal of Clinical Nutrition in January 2013, had similar results. Researchers found that both types of beverages may contribute to metabolic syndrome and diabetes.
One theory is that diet soda may stimulate appetite and increase the desire to eat sugary foods. Some studies also suggest that aspartame may cause a similar glycemic response as does sugar. Additionally, artificial sweeteners may alter the gut microbiota, affecting body weight and metabolism.
Another large-scale study published in Applied Physiology, Nutrition, and Metabolism in May 2016, linked aspartame consumption to glucose intolerance in people with obesity, but not in lean individuals. Medical professionals, including those at the Mayo Clinic and Joslin Diabetes Center, state that aspartame as no effect on blood sugar levels and can be safely consumed by those with diabetes.
As you see, the research is mixed. Diet Coke's sugar and calories are not an issue. Aspartame, on the other hand, may not be safe.
All in all, an occasional glass of diet cola is unlikely to affect your health. Enjoy this beverage in moderation and keep an eye on your total calorie intake. Consider replacing diet soda with fruit-infused water, lemon water or unsweetened iced tea. Carbonated water with lemon or lime juice and fresh mint leaves is a good choice, too.
- CDC: "Consumption of Diet Drinks in the United States, 2009‒2010"
- Current Development in Nutrition: "Diet Soda and Sugar-Sweetened Soda Consumption in Relation to Incident Diabetes in the Northern Manhattan Study"
- Diet Coke: "Original Diet Coke"
- PubChem: "Phenylalanine"
- Mayo Clinic: "My Favorite Diet Soda Has a Warning About Phenylalanine. Is Phenylalanine Bad for Your Health?"
- Trends in Endocrinology and Metabolism: "Artificial Sweeteners Produce the Counterintuitive Effect of Inducing Metabolic Derangements"
- Diabetes Care: "Nonnutritive Sweeteners: Current Use and Health Perspectives"
- Pediatric Obesity: "Consumption of Low‐calorie Sweetened Beverages Is Associated With Higher Total Energy and Sugar Intake Among Children, NHANES 2011–2016"
- American Journal of Clinical Nutrition: "Consumption of Artificially and Sugar-Sweetened Beverages and Incident Type 2 Diabetes in the Etude Epidémiologique Auprès Des Femmes De La Mutuelle GénÉrale De L'Education Nationale–European Prospective Investigation Into Cancer and Nutrition Cohort"
- Nature: "The Weighty Costs of Non-Caloric Sweeteners"
- Applied Physiology, Nutrition, and Metabolism: "Aspartame Intake Is Associated With Greater Glucose Intolerance in Individuals With Obesity"
- Mayo Clinic: "Artificial Sweeteners: Any Effect on Blood Sugar?"
- Joslin Diabetes Center: "Correcting Internet Myths About Aspartame"