To put it in a less dumb way, sugar induces significant physiological responses throughout the body, but specifically when dealing with the reward system of the brain, certain sweeteners (namely aspartame and what are generally listed as "sugar alcohols") illicit nearly identical responses to actual sugar.

Your brain knows the difference. At least at first. But as time goes on, your body adjusts to the differences and the line between sugar and these sweeteners becomes very blurry. Your body will treat the sweeteners exactly as it does sugar. Subjectively, you'll notice this initially as the off taste of diet soda eventually goes away. You'll start to crave these instead of the normal sugary drinks you used to drink. If you abstain long enough, the non-diet counterparts will actually taste off to you instead. Objectively, we know this process (or something very similar, depending on your view of how the brain operates) exists because of things like sweeteners still inducing an insulin response, albeit generally milder, despite there being no actual sugar ingested.

One popular misconception is that artificial sweeteners are somehow capable of disobeying the laws of physics and make people fat, or cause people that are fat to stay that way. It is not possible to spontaneously generate energy with nothing to fuel it. The metabolic process relies on calories, and if there are no calories, that process breaks down. Fat gain or loss is dictated solely on calories in versus calories out, assuming the person is otherwise functioning normally. Fat is created when an excessive amount of calories are consumed in too short of a time frame for the body to make effective use of them. The processes and dysfunctions of the body that are capable of changing this are few and far between. There is no magic pill that makes you lose fat, and the ones that come anywhere near it inevitably have so many other negative effects on the body, the person is better off just being fat. Why people think there are magic substances that somehow cause the opposite effect is just one of those things I guess.

So, assuming we can agree that people ingesting artificial sweeteners are in fact not perpetual energy machines, we move onto the next popular misconception, that being that the brain somehow "knows" it is being "tricked", and after exclaiming "Egads! The scoundrels!" "makes" itself go on a wild hunt for sugar. This process doesn't exist. If it does, we don't understand how or why. If you take a person that is a healthy weight, and give them a bunch of aspartame, they don't suddenly start gaining fat or start going on sugar binges. Even if someone doesn't actually bother with the science, that should be evidence I think most can agree falls under common sense.

But, Jeremiah, you say, people that drink aspartame et al gain weight. They do get fatter. Which is half true.

One thing about artificial sweeteners is they are actually full of sodium. And what happens when you eat a bunch of salt? Well, you have to drink a lot of water. And what happens to that water? It stays in your body until you can piss out all the extra salt. So what do we get when we mix a bunch of water with a bunch of sodium, aka diet soda? We get water retention. Which, while in fact is not fat, does make you gain weight and look bigger.

The problem with aspartame isn't that it is going to give you cancer, or that it magically makes you have more fat, or that it even contains sodium, but that your brain keeps thinking it is getting sugar when it isn't.

Now, let's say instead of having an eating disorder, you are a heroin addict. But instead of giving you heroin, we give you another chemical that your brain essentially processes like heroin. Well, even though other processes in your body react differently to this new substance, your brain still acts like it is getting heroin. So you stay addicted, and still crave heroin (or more specifically the effects of heroin). However, those other differences make it at least slightly easier to stop wanting heroin. And thus there was methadone. Aspartame is to sugar as methadone is to heroin. It's not a perfect analogy but a pretty good one. Unfortunately we're talking about food and not recreational drugs, so stopping sugar intake (or rather carbohydrates) is a pretty unrealistic goal. Even if you use only artificial sweeteners, you still have to consume carbohydrates. So the problem requires a constant, lifelong vigilance where you are tested literally every day.

Thankfully, there is a quasi-solution, in that there are artificial sweeteners that your body doesn't process as sugar. They don't reinforce the dysfunctional reward pathways that feed eating disorders. But at the same time, they are sweet, and taste good, and remind you of sugar. And that's where we get to the whole point of this tirade.

99.99% of the time, your mind is what makes you fat. It's not because of shitty genes, or artificial sweeteners are magic, or that high fructose corn syrup makes you into a zombie. You choose to eat and drink in a way that makes you fat. Whether it be guzzling down a 2 liter in an hour, or eating 100 oranges a day, or consuming pounds of basically anything in a single meal, you gain fat because you eat too damned much, too damned fast, and you don't exercise enough.

Nigger.

Shit's poison Yo.....Lots of stuff to find on Aspartame. It's even been found as a hidden ingredient in some meds.