The reason it has 0 calories (technically not 0, but due to laws its close enough to 0 that it’s allowed to say 0) is because the chemicals that make it sweet arent properly “digested” by your body, meaning they dont become fuel (aka, calories).
So yes, just like sunbathing in front of a picture of a sunny beach won’t give you a tan, drinking something that isnt converted into calories by your body won’t make you gain weight.
HOWEVER, there are studies linking sweetened drinks to higher hunger and/or thirst. So while the drink itself wont make you gain weight, it **could** cause your behavior to change so as to be more likely to gain weight via other methods.
Latest Answers