Type the sugars fructose used to sweeten soft drinks, cakes and chocolate, sugar is the most "lethal", said the scientists warn.
Fructose can increase bad cholesterol and the risk of diabetes that lead to heart attack or stroke.
Although fructose is also found in fruits, the effects of natural fructose can be neutralized easily by the body, in contrast to fructose in processed foods as well as sweet menuman.
Fructose is added to sweeten food products and beverages judged to be worse for the body than glucose.
In the study, rats fed a fructose water for two months experienced a surge in weight than rats given sugar water. The rats also had higher levels of harmful fats in the bloodstream and unhealthy condition of the arteries.
Food expert Professor Marta Alegret from the University of Barcelona advise people to avoid products with added fructose.
