We evolved to be able to process fruit, sugar, and alcohol because our big fat brains needed energy. So at the time when monkey like creatures were turning into human ancestors we needed the sugars and carbs to fuel our ever growing brain because leaves and shit were not cutting it. However, during the process of evolution being able to process and absorb crap never went away because it's not like it was a bad thing (until now). So at one point, sugar was good, very good, now it is bad, very bad. Hopefully evolution fixes that.