If you’re on a diet, it makes sense to eat diet foods and drink diet sodas, right? The diet food industry certainly hopes you think so. In reality, diet foods and drinks can be just as bad for you as their regular counterparts.

Diet foods come in two main varieties: sugar-free and fat-free. Sugar-free foods are sweetened with artificial sweeteners like aspartame, saccharine, or sucralose. These chemicals taste so sweet that they trigger your body to produce insulin, a chemical that regulates blood glucose levels.

But since the foods don’t contain sugar, the insulin doesn’t have anything to do once it’s in your system. This causes hunger and lethargy, and might make you eat much more than you normally would. Over time, your body could become resistant to the excess insulin, paving the way for diabetes.

Fat-free foods are typically enhanced with extra sugar and MSGs. These make the foods taste better, but they can raise the blood sugar to unhealthy levels. Foods with no fat content tend to get processed very quickly by the body, leaving you hungry again in short order.