I don't think theres a scientific way like there is with WW, this is one of the reasons I have asked a friend to pick up the shopping guide for me. What I have done to help as well is create a table on word with all the foods that have passed through my lips that have syns, or foods I like with syns, I keep a note of the syns for future reference. Are you able to get onto the slimming world website, because theres a syns calculator on there - shame they don't bring out one you can buy and carry around in your handbag!