Diet and zero-calorie drinks generally contain a combination of water and some variety of artificial sweetener. Artificial sweeteners commonly used as of 2015 include aspartame, sucralose and acesulfame potassium. Beverages such as water and plain brewed tea are naturally calorie-free.
The majority of calories in conventional sodas and juices are derived from sugar. Removing the sugar from these drinks reduces or eliminates the caloric content. Many diet drink manufacturers use artificial sweeteners to maintain the flavor of the product while removing the calories.
Some diet sodas, such as diet Coca Cola, are made with aspartame. Aspartame is a common artificial sweetener found in many calorie-free and calorie-reduced beverages. As of 2015, some researcher have speculated that aspartame has the potential to be carcinogenic. These claims have not been conclusively verified, however diet Coca Cola offers an additional variety that is made with the sugar substitute Splenda, a mixture of sucralose and acesulfame potassium..
Acesulfame potassium and sucralose are other varieties of artificial sweetener that commonly appear in zero-calorie drinks. Acesulfame potassium is sold under the brand names Sweet One and Sunett. This sweetener is approximately 200 times sweeter than sugar, and it adds negligible calories when used to sweeten diet sodas.