Answer: The short answer is no. There is no cause-and-effect relationship established with drinking diet soda and metabolic syndrome (which is a host of obesity-related diseases). An observational study (arriving at conclusions from assumed premises) published in Circulation, July 2007, looked at the dietary habits of subjects in the long-running Framingham heart study and concluded there was an association. However, the subjects in the study already had weight-related health issues and were likely drinking diet in place of regular soda at the advice of their doctor. Keep in mind that some people may drink a Diet Coke with their cheeseburger and fries to minimize the calories of the meal.