CORE is like Andrea said based on a group of whole foods. You eat foods from an apporved list without counting points. You eat when you are hungry and stop when you are satisfied. Like FLEXers you get the 35 weekly points to use towards non core foods. Many people like core's no counting, the foods on the list are healthy, satisfying and varied. I don't find core works for me and my life style b/c one, I don't know how to stop when I am satisfied instead of stuffed. But core foods are the best bang for your points buck so to speak, so I include tham any chance I get.