"It's like opening a can of freedom!"
Scientists noticed a strange trend: People who drink diet soda do not in fact lose any weight. They reason appears to have something to do with how your body processes sugar.
You see, with the exception of one organ in particular, your body is kind of a dumbass. That's why, when you wash down your meal with a half-gallon of fake sweetness, your gut is all "Dur, sugar!" and tells your pancreas to get all revved up to process said shitload of sugar. Because your pancreas is not the sharpest tool in the shed, it starts cranking out insulin. This is a problem, since there is, in fact, no shitload of sugar to process.
"I just put straight meth into my coffee now, and I've lost 20 pounds in four hours."
This kicks off a vicious cycle in which your body A) absorbs more of the sugar that you ingest from other foods and B) craves more food, since you got it all aroused with promises of sugar overload and then cockblocked it with a bunch of counterfeit sugar instead. Researchers point out that this "might explain in part why obesity has risen in parallel with the use of artificial sweeteners."
So while you may think you're helping out your diet by allowing yourself some low-calorie (but still sweet) alternatives, chances are you're actually screwing over your waistline in the long run.