Six different individuals have filed a lawsuit against Coca-Cola, PepsiCo, and Dr Pepper Snapple Group Inc. for misleading advertisements regarding the companies' diet soda options.

The six individuals, who have all struggled with obesity and looked to diet sodas to help with weight loss, claim that the aspartame, a low-calorie sweetener that's used in the diet sodas, have made them gain weight instead.

Aspartame, a sugar substitute that's also sold under the name NutraSweet and Equal, is used heavily in "diet" labeled foods. According to Boston Magazine and a 2016 study from Massachussets General Hospital, when aspartame is ingested, a compound called phenylalanine is produced. Phenylalanine has been proven to interfere with IAP, or intestinal alkaline phosphate, an enzyme that helps prevent diabetes and weight loss. According to that same article, artificial sweeteners have been shown to make consumers hungrier, leading them to binge eat in the long run.

Therefore, with these proven studies, the suits claim that marketing these beverages as "diet" is false, misleading, and unlawful.

Derek Smith, whose law firm is the lead counsel for all three lawsuits, said that their case will focus on aspartame, but noted that all artificial sweeteners behave the same in our bodies.

Coca-Cola and Dr Pepper Snapple has called the lawsuit "meritless" and claims to "vigorously defend against it." PepsiCo has yet to make an official statement.