You may have heard about recent studies showing that people who drink diet soft drinks have a higher risk for diabetes, high blood pressure, heart attacks and strokes than those who do not drink diet drinks. But in fact, researchers have not been able to say that the diet drinks are to blame. Most of those studies are observational, meaning they simply report what they observe. Observational studies are not designed to determine cause and effect. That requires a different kind of study.
In addition, a recent study showed other differences between people who drank diet sodas and those who drank regular sodas. Overall diet, or food intake, is one important difference.