Research suggests that consuming diet soda, such as Diet Coke, may be linked to various side effects, including weight gain and water retention. However, the relationship between diet soda and weight gain is not entirely clear, with some studies indicating that diet soda alone may not cause weight gain, but rather its combination with other factors like carbohydrates. The exact effects of diet soda on the body are still being explored, with some outlets reporting on potential symptoms and side effects to watch for.