Might be related to weight gain

Researchers' findings on the topic of diet soda consumption and weight gain are conflicting. According to one research of 749 older adults, those who frequently drank diet Coke tended to experience greater increases in belly fat over a 9-year period than those who didn't. Another study with 2,126 participants revealed that having at least one soft drink daily was linked to an increased chance of developing metabolic syndrome. Further evidence from the Journal of the American Geriatric Society showed that added diet soda intake is associated with added inches around your waist.

On the other hand, some studies have not discovered a link between artificial sweeteners or diet drinks and body weight. In addition, other studies have shown that diet soda, particularly when used in place of sugar-sweetened beverages like soda, may actually cause weight loss and a reduction in appetite. The connection between diet soda consumption and body weight requires a lot more study.