It can cause obesity.

The sweetness of sugar-free cola comes from sweeteners such as aspartame, sucralose (sucralose), and acesulfame. Of the three sweeteners, sucralose is the sweetest at 600 times that of sucrose, aspartame is about 200 times that of sucrose, and acesulfame is 130 times that of sucrose. Thus, adding a very small amount of sweetener gives a taste comparable to that of regular cola.

A review published in Obesity Factors summarized 30 recent studies on artificially sweetened beverages between 2013 and 2015. From data from 244,651 subjects, the researchers found a significant correlation between beverages with large amounts of added sweeteners and both overweight and obesity.In 2017, a team of Israeli researchers had a study that showed that feeding acesulfame to mice for four consecutive weeks led to a change in the mice's intestinal flora and an increase in the male mice's weight.

"Most epidemiologic studies have found that consumption of sweeteners is associated with higher body weight. In other words, people who ate more sweeteners were fatter than those who didn't." It has also been shown that sweeteners, although they contain no sugar, activate sweet receptors in the pancreas and small intestine, causing insulin concentrations in the body to rise. And with elevated insulin levels, fat breakdown decreases and synthesis increases, making it easier to become obese.

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In 1962, Crown Cola introduced the world's first DietRiteCola, setting off a low-sugar beverage craze that took the nation by storm. Coca-Cola and PepsiCo took aim at the huge opportunities in the diet market and followed with their own sugar-free colas. It's true that sweeteners don't produce calories, but sweeteners can fool the tastebuds, but they can't get out of the brain's way. Sugar and sweeteners both stimulate the production of sweetness, but the difference is that sugar also stimulates the brain to produce satiety signals, telling the body to "eat enough, you can stop," but sweeteners do not. In other words, sweeteners make you fall into another trap of "not eating enough".