The fake sugar triggers your body's mechanisms for processing real sugar, so when that real sugar never hits you start craving more sugar. The desire for that occasional cookie and other sweets you eat may be a biproduct of zero sugar sodas: https://kids.frontiersin.org/articles/10.3389/frym.2019.00051
Abstract Why do sweet things taste so good? Sugar provides our bodies with energy (in the form of calories), which is probably why we have evolved to find it so delicious. Although we need calories, too many can make us gain weight, which can cause weight-related illnesses, like type 2 diabetes, and high blood pressure. Artificial sweeteners were invented to taste like sugar but have almost no calories; the goal was to have a sweetener that we could eat more of without developing diseases or gaining too much weight. However, artificial sweeteners sometimes have negative effects on the body and brain that sugars do not. Our brains, stomach microbes, and pancreases process artificial and real sugars differentlywhich can cause us to eat more, gain more weight, and have a harder time digesting the real sugars that our bodies need. Artificial sweeteners should be consumed in moderation, because they trick our brains and bodies into thinking they are treatswhich can sometimes have negative health consequences.
Our brains and bodies have different responses to artificial sweeteners and sugars because these substances are different from one another at the level of microscopic molecules. Reward pathways are like racetracks for neurons in our brains that when excited result in the release of chemicals (such as dopamine, a common neurotransmitter) that make us feel good. Think of how good it feels to eat when you are hungry, or to have ice cream or cookies for dessert! Consuming sugar activates our reward pathways, which explains from a neurological perspective why we like the taste of it so much. Artificial sweeteners only partially activate reward pathways, as they are sweet (which we enjoy for pleasure), but do not have the calories that we need for energy [3]. By not fully activating reward pathways, artificial sweeteners can be potentially harmful because they may, in a way, trick our brains, causing us to overeat in order to feel satisfied, or to crave even more sweetness later on. After consuming artificial sweeteners, people experience less pleasure, which should decrease appetite, yet they tend to eat more, and to choose foods that have a higher calorie count than people who consume nothing sweet, or those who consume real sugar [4]. Artificial sweeteners may make us crave real sugar even more, whereas cutting out sugars and artificial sweeteners from ones diet can lead to a decrease in sugar cravings in as little as 1 week [3].
They're also FAR sweeter than real sugars and mess up your body's sense of taste: https://cimgpeds.com/artificial-sweeteners-make-you-crave-more-sweets/
Has your child ever had a no sugar, zero calorie food or drink that was sweetened with an artificial sweetener? As parents we think we are doing the right thing by cutting down on their sugar intake, but some studies suggest links between nonnutritive sweetener (i.e., artificial sweetener) use and changes in appetite and taste preferences, as well as in the gut microbiome, which may affect blood sugar levels and lead to metabolic syndrome, insulin resistance, diabetes, and weight gain.
Artificial sweeteners are 180 to 20,000 times sweeter than sugar so they can possibly alter the consumers taste buds to have a higher tolerance for sweetness and thus crave sweeter and sweeter foods and drinks over time. Fortunately, One study suggests that taste buds can be reset if the individual who has built up a tolerance to sweetness goes a long period of time without consuming any kind of sugar.
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