Syns are needed for SW to work because without them it would be a restricted diet which would make you feel deprived and therefore more likely to fall off the wagon. This is a lifestyle plan that incorporates foods that you eat everyday (which includes sugar, honey, oil, chocolate etc).
Imagine if we could NEVER have sugar or extra cheese or wine or whatever, what then? Do we avoid them forever? Or just for the duration of the diet? And then what happens when we're done with the diet and start eating them again? Yep you guessed it... Back to square one. So rather than having free reign over treats, which is what got us here in the first place

, we can enjoy them in controlled amounts so we can still lose weight but not feel deprived. And most importantly it turns what could be a "diet" into a healthy eating plan that we can sustain for life.