“HOW CAN this drink have zero calories and be sweet at the same time?” is a common question  from those who try zero-calorie drinks for the first time. Zero-calorie drinks, also known as “diet sodas,” are drinks that contain almost no calories. Following the current consumer trend of pursuing a healthy diet, many soda companies in Korea are heavily investing in the production of zero-calorie drinks. For example, in April, Lotte Chilsung Beverage launched a new line of zero-calorie drinks called Tams Zero, and Nongshim released two flavors of the zero-calorie drink Welch’s Zero. The companies made substantial profits through these products; compared to last year, Lotte Chilsung Beverage’s net profit increased by 31.8% and Nongshim sold more than 13 million cans of Welch’s Zero during the first three months of its release[1]. The rising popularity of zero-calorie drinks makes it pertinent for us to understand the science behind them, especially as it directly impacts our health.

The history of zero-calorie drinks

No-Cal, produced in the United States in 1952 by Russian immigrants Hyman Kirsch and his son Morris Kirsch, was the first zero-calorie drink and was targeted at diabetic and cardiovascular patients. After witnessing No-Cal’s success in the soda market, other soda companies including Coca-Cola joined in the game as well. Coca-Cola’s first diet soda was named “Tab," and like No-Cal, Tab was also originally advertised to diabetic and cardiovascular patients. However, soda companies soon found it more profitable to target women trying to lose weight. They made commercials with models proclaiming that drinking diet sodas make women “more beautiful[2].” Still, some soda companies like Dr. Pepper struggled as the public continued to view their zero-calorie products as beverages for diabetics and patients experiencing health issues[2].  

   Until recently, soda companies struggled in the Korean market as well. Zero-calorie sodas were first introduced in Korea in the early 2000s; however, back then, a majority of the public viewed consuming sodas as unhealthy[3]. Moreover, due to the difference in taste between a soda and its “diet” version, many Koreans did not prefer drinking zero-calorie sodas[3]. However, with the rise of the “healthy pleasure” trend and food science advancing to the point of producing a zero-calorie drink that tastes identical to the original soda, the zero-calorie beverage market grew exponentially in Korea. The “healthy pleasure” trend refers to a lifestyle that manages health while pursuing happiness[3]. For example, a common dieting trend in Korea is for people to heavily restrict their food intake in an attempt to reduce their weight. However, with the rise of the “healthy pleasure” craze, people have begun looking for meals and drinks that are delicious and low in calories—zero-calorie sodas being a perfect fit for this trend. 

Sugars and artificial sweeteners

   The key to producing zero-calorie drinks lies in reducing the amount of sugars; sucrose or high fructose corn syrup are common ingredients added in soft drinks to enhance their sweetness[5]. Sucrose and high fructose corn syrup are high in calories, containing 387 kcal and 286 kcal per 100 g, respectively[6]. However, this does not mean that sugars are downright harmful to our health; in fact, they are a quick energy source that allows us to perform everyday tasks. This is because the high calorie content of sugars like glucose makes it so that even a small amount of sugar can be metabolized into a disproportionately large amount of energy that powers our body. Moreover, sugars are found in every food group, from dairy products to protein-based foods. However, an excessive intake of added sugars––sugars that are added while processing food––leads to prolonged high blood sugar levels as well as insulin and leptin resistance, which in turn lead to weight gain and chronic diseases[10]. The American Heart Association prescribes 24 g of added sugars for women and 36 g for men per day[7]. As even a 330 mL can of Coke exceeds the recommended amount of sugar intake per day for males by 3 g, health experts discourage people from drinking sodas on a daily basis[6]. 

In light of all this information, many turn to zero-calorie drinks and low-calorie foods that substitute sugar for a healthy alternative with fewer caloric content. There are three main categories of sugar substitutes: natural sweeteners, sugar alcohol, and artificial sweeteners. Natural sweeteners include naturally occurring, sweet substances such as honey and stevia. Sugar alcohols are found in fruit and plants and are commonly used in “sugar-free” foods[8]. Artificial sweeteners are synthesized sugar substitutes, and they are mostly used to substitute sugars in zero-calorie drinks. 

What makes zero-calorie drinks have zero calories?

The main reason why artificial sweeteners have fewer calories than regular sugars and can still be an effective substitute for them is because they cannot be metabolized into a form of energy for our bodies but still have the intensely sweet flavor we crave for[9]. For example, aspartame and sucralose, the two main types of artificial sweeteners used in zero-calorie drinks, are 200 times and 600 times sweeter than table sugar, respectively[10]. Thus, even if the sweeteners do have calories, the amount of sweeteners required to flavor the drinks is minuscule, allowing the drinks to be low in calories. Considering this information, it is interesting to note that almost all of the zero-calorie drinks we can find nowadays do not technically have zero calories, as the current South Korean Ministry of Food and Drug Safety allows drinks with less than 4 kcal per 100 mL to be advertised as “zero-calorie drinks[11].” 

“Sweetener scare”

   For decades, many experts have raised safety concerns regarding the artificial sweeteners used in zero-calorie drinks. Apprehensions toward consuming zero-calorie beverages escalated after the United States’s Food and Drug Administration (FDA) banned cyclamate––one of the main ingredients in Tab––in response to a 1969 report showing that cyclamate could cause bladder cancer[12]. Likewise, aspartame, one of the most popular artificial sweeteners, is thought to have links with brain damage and schizophrenia[10]. Despite being confirmed by the FDA and numerous other health agencies that aspartame and other permitted sweeteners are safe for consumption, the “sweetener scare” persists in public discussion.

Indeed, there are several things to be cautious about when consuming zero-calorie drinks. Firstly, excessive consumption of sugar substitutes can lead to bloating or diarrhea as they cannot be metabolized well, meaning that our bodies may not be able to digest them properly[3]. Additionally, it has been found that even though sugar substitutes, generally speaking, are unable to be metabolized, some sweeteners like maltitol can still raise a person’s blood sugar level depending on the procedure through which they were processed[3]. Besides, the acidity of diet sodas can weaken tooth enamel––the hard mineral layer that protects our teeth––and cause dental issues[13].

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   For those who want to gradually reduce their consumption of sugar-packed soda, switching to zero-calorie drinks can be a good start. However, it is important to be aware of the science behind zero-calorie drinks before including them as part of your weight-loss routine, being careful not to drink an excessive amount of diet sodas under the impression that they are an unconditionally healthier substitute.

[1] Yonhap News Agency

[2] The New York Times

[3] The Asia Business Daily

[4] Medical News Today

[5] Business Watch

[6] Coca-Cola

[7] The American Heart Association

[8] Yale New Haven Hospital 

[9] Harvard T.C. Chan School of Public Health

[10] Healthline

[11] Segye Ilbo

[12] National Museum of American History

[13] Espire Dental