Are Diet Drinks Bad For You?

by Marixie Ann Obsioma, MT, undergrad MD on July 10, 2019
Last updated on May 23, 2021

You must know that a single can of soda contains 140 calories and it is certainly not a health elixir! But with news about people downing diet soda regularly and yet they remain looking young and perfectly healthy, perhaps you have not thought about controlling your intake. However, the truth is, you are not doing yourself any favor.

a can of diet coke at the beach

Regular or diet, soda is not a healthy choice. It contains chemicals that may cause chronic illnesses. If you are far from breaking your diet soda habit, keep reading to know more about the many science-based reasons that will convince you to ditch that diet for good.

It is Not Nutritive

While the recipes are different from brand to brand, common ingredients in a diet soda yield zero to very few calories and have no significant nutrition.

  • Instead of using sparkling water, sodas are made by infusing water with carbon dioxide under pressure (1, 2).
  • They have artificial sweeteners like saccharin, aspartame, sucralose, and Stevia, which are 200-13,000 times sweeter than regular sugar (2, 3).
  • The acids used to add tartness to carbonated beverages may cause tooth enamel erosion (2).
  • Anthocyanins, carotenoids, and caramels are favorite soda colorings (2).
  • Different types of natural and artificial flavorings are used in diet soda. It may include fruits, cola, and herbs (2).
  • Preservatives are needed to help extend the shelf life of diet soda. The most commonly used ingredient is potassium benzoate (2).
  • Other varieties of diet sodas add vitamins and minerals for advertisement as a healthier no-calorie alternative (2).
  • Diet sodas also contain caffeine. In fact, a single can of diet Pepsi and diet coke has 34 and 46 mg of caffeine, respectively (4, 5).

Its Effects on Weight Loss Are Inconsistent

Tagged as calorie-free, it’s natural for many people to assume that diet soda can be a good weight loss tool. However, there are mixed studies and some suggest otherwise. Many have found that the consumption of diet soda and the use of artificial sweeteners can increase one’s risk of obesity and metabolic syndrome (6, 7, 8, 9). Experts also suggest that diet soda may stimulate hunger hormones, thus increasing appetite. It also affects sweet taste receptors and prompt dopamine responses in the brain (10, 11, 12, 13).

These carbonated drinks contain zero to very few calories. People have a tendency to increase their intake of sweet and high-calorie foods, which may lead to weight gain. However, evidence of this varies in human studies (3, 10, 14). One theory suggests that weight gain is caused by existing bad dietary habits (15, 16). Experimental studies also found that drinking diet soda instead of sugar-sweetened drinks can help you slim down (17, 18). Another study investigated overweight individuals for a year. One group was asked to drink 24 ounces of diet soda daily, while the other group sticks to water. Results showed that the diet soda group had lost approximately 6.21 kg as compared to 2.5 kg in the control group (19).

However, to add to the confusion, there is evidence showing that studies funded by the artificial sweetener industry get more favorable results. This bias makes the validity of their results highly questionable (20). All in all, more research are required to confirm the effects of diet soda on weight loss.

It May Increase One’s Risk of Diabetes, Heart Disease, and Stroke

The absence of calories or sugar in a drink does not make it healthier, especially for those who are at risk or have diabetes. One recent study followed more than 66,000 women for 14 long years. Though other factors should still be considered, researchers found a linked between sweetened drinks and a higher risk of type 2 diabetes (21, 22, 23, 24). Drinking even just a single serving of an artificially sweetened drink daily can increase your risk of type 2 DM by 8-13% (25, 26). Conversely, one review concluded that diet soda is not associated with an increased risk of DM. It could be explained by the patient’s existing health status, BMI, and weight changes (27, 28).

Diet soda may also cause high blood pressure and heart disease. Four studies involving more than 220,000 people found that for every serving of artificially sweetened drink per day, you can increase your risk of high BP by 9%. Other studies obtained the same results (29, 30, 31).

One study, based on observational data, also linked diet sodas to stroke (32). Postmenopausal women who drank 2 or more diet sodas daily were also linked to an earlier risk of heart disease, stroke, and early death (33).

More experimental research should be done to establish the association between diet soda and DM, heart disease, or stroke.

It May Cause Kidney Problems

There is evidence pointing to diet soda as a possible cause of chronic kidney disease. One recent study looked into more than 15,300 people and found that the risk of having end-stage kidney disease increases with the amount of diet soda taken per week. Those who had more than 7 glasses per week had nearly twice the risk (34). This is possibly caused by the high phosphorus content of sodas, which loads the kidneys with acid (34, 35).

But studies investigating the effects of diet soda on the development of kidney stones have mixed results. One observational study reported that diet soda drinkers have a slightly increased risk of kidney stones, but this was much smaller than for regular soda. No other research has been done to support these claims though (36). On the other hand, one study believed that the high malate and citrate content of some diet soda brands can help cure kidney stones, especially in patients with uric acid stones and low urine pH. However, studies on humans are needed (37).

It’s A Risk Factor for Preterm Labor and Childhood Obesity

Diet soda is not recommended for pregnant women because it may cause preterm labor and childhood obesity. This has been proven by a Norwegian study involving more than 60,700 patients. Results showed that the intake of sweetened beverages may increase your risk of preterm labor by as much as 11% (38).

Another research supports these findings. Women who took one serving of diet soda daily were 1.4 times more likely to give birth preterm (39). The exact mechanism as to how diet soda may cause preterm labor remains to be unknown.

Another worrisome finding is that drinking artificially sweetened beverages during pregnancy is significantly associated with an increased risk of childhood obesity (40). One study found that regular consumption of diet drinks doubled the risk of a baby being overweight at 1-year-old (41). More research is needed to check on the potential biological causes and long-term health risks for kids exposed to sweetened sodas while in the womb.

Other Effects

There are more documented health effects related to drinking diet sodas. These include the following:

  • Diet soda may not be healthy for your skin. It has a dehydrating effect, which may cause acne. This can be remedied by keeping yourself well hydrated.
  • Artificial sweeteners affect the normal bacteria in the gastrointestinal tract, causing reduced blood sugar control. This can increase your risk of type 2 DM, though more research is needed (42, 43).
  • Both regular and diet sodas may decrease bone mineral density in women. Phosphorus and caffeine also inhibit normal calcium absorption (3).
  • Many observational studies have linked depression to people who drank 4 or more regular or diet sodas per day (44).
  • While some research proved that replacing regular soda with diet soda can help reduce fatty liver, others found no effect (45, 46).
  • There are mixed studies about carbonated drinks causing reflux or heartburn (1, 47).
  • Though most research does not show evidence linking diet soda with cancer, there were some studies showing a slight increase in multiple myeloma and lymphoma in men (48, 49).

Key Takeaway

Studies on diet soda have produced conflicting evidence since most were just observational. They observe trends and lack of information about the cause and mechanism of action. Therefore, while some of these studies are alarming, more experimental and in-depth studies are needed to draw a conclusion about the health effects of diet soda. Regardless, one thing is for sure. Diet soda is not nutritious and does not add any value to your health!


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