Fructose is a simple, monosaccharide sugar, found in plants. Fructose and Glucose when combined form disaccharide Sucrose (added sugar). Sugar decomposes in these two simple components in the digestive tract before it goes to the bloodstream. After years of research, it has come out that sugar can cause harm to our bodies. Glucose is found in and needed by every cell of the body, but not the fructose. The liver is the only organ, which metabolizes fructose in any considerable amount.
When we are doing a workout or having small fructose intake, the liver will convert it into glycogen (glucose is stored in the body in the form of glycogen). On the other hand, if we are not doing any workouts or having large fructose intake, the liver will turn it into fat. Hence, it causes insulin resistance in the liver, which means that the liver is no more able to see insulin in the bloodstream. High fructose levels also lead to cholesterol, heart diseases, blood sugars, type II diabetes, obesity, chronically elevated insulin, and triglycerides. So, fructose from sucrose is bad, but not when taken from the natural FRUITS.