It's not as simple as you think... Science isn't even 100% sure yet what excatly causes obesity, the research is still ongoing...One thing that science does know is that, it's not just the calories in sugar that contribute to obesity. More and more research points to the fact that sugar has an affect on hormones which in turn causes human body to store fat...I think that the biggest problem with sugar is that too many people use it as a comfort food for pleasure and snacking instead of using it strictly as an energy source during hard physical activities.