Diet drinks offer the hopes that people will lose weight or in the long run not gain as much weight as they normally would drinking a high sugar drink. The truth though is this, the additives and aspartame in the drinks themselves that allow it to be labeled "diet" are actually causing far worse problems for individuals. In many cases not only are these addictive in nature but are causing neurological and physical problems.
Aspartame is a chemical, chemicals can mess up the way people think, reason, and function physically. There are many healthy alternatives to artificial sweeteners. If it the carbonated beverage you like than get some carbonated flavored water. This is a serious thing on our hands for many people who are drinking up to a liter a day of their favorite "diet" drink. Look into this and see the articles below for more research and evidence of what is happening to your body chemically by drinking unhealthy drinks.
Dangers of Diet Coke and Aspartame