If you’re going to munch on chocolate, choose dark chocolate. It’s something that has gained popularity as growing research points out the various health benefits of eating dark chocolate in moderation.

Studies have shown that dark chocolate, which is rich in flavanols — a type of healthy antioxidant — can improve your cardiovascular system. Chocolate is also filled with other types of antioxidants and flavonoids, the latter of which are found in various fruits and vegetables. Flavanols are the main type of flavonoid in cocoa, and have been shown to improve vascular health by lowering blood pressure, improving blood flow to the brain and heart, as well as boosting the clotting properties of blood platelets.

In fact, that strong bitter taste in really dark chocolate comes from flavanols. That’s why processed chocolate — which goes through plenty of steps to reduce that bitter taste — is sweeter and contains far less flavanols than pure cocoa.

Now, researchers suggest that flavanols could help fight obesity as well as type 2 diabetes. In the study, Andrew P. Neilson and his co-authors pinpointed a certain combination of antioxidants that actually prevented lab mice from gaining extra weight, and also led to decreased blood sugar levels.

The researchers gave different groups of mice particular diets — some were high-fat and others low-fat. The high-fat diets contained levels of flavanols. One specific type of flavanol known as oligomeric procyanidins (PCs) made a much more significant improvement for preventing obesity and diabetes than the other compounds. Oligomeric PCs were able to keep the weight down among mice on high-fat diets and also raised glucose tolerance.

“Oligomeric PCs appear to possess the greatest antiobesity and antidiabetic bioactivities of the flavanols in cocoa, particularly at the low doses employed for the present study,” the researchers state. So before reaching for that bag of processed candy chocolate on the shelf, choose dark chocolate — the higher percentage of dark chocolate, the better.