Black soya beans could be a key weapon in the fight against obesity, scientists claim. A diet rich in the beans could also help lower cholesterol levels and aid in the prevention of diabetes. Researchers fed rats a fatty diet, supplemented with various levels of black soya. After two weeks, those getting 10 percent of their energy from black soya had gained half as much weight as those in the control group. In the same rats, blood cholesterol fell by 25 percent and LDL (so called 'bad') cholesterol fell by 60 percent. Experts believe that the soya protein could slow down the metabolism of the liver,reducing the production of fatty acids and cholesterol. Reducing the amount of fat in the body would then protect against diabetes.