People who lose weight often put it back on again soon afterwards - but scientists believe that a simple berry could break the vicious cycle of yo-yo diets. The chokeberry (Aronia) - an antioxidant that is available as a dietary supplement in healthfood stores - regulates weight gain and blood glucose levels, researchers have discovered. So far, the supplement, marketed as Cellberry, and manufactured by Integrity Nutraceuticals International, has only been tested on laboratory rats, but researchers are confident that similar beneficial effects will be seen in humans, too. Chokeberry is rich in anthocyanins, and these appear to improve blood sugar levels, and the functioning of insulin - both key factors in controlling weight. Researchers tested the supplements on 18 'pre-diabetic', or insulin-insensitive, rats. The rats that had been given the supplements for six weeks weighed less than those in the control group. (Source: Proceedings of the Experimental Biology conference, Anaheim, California, April 25, 2010).