The others above are correct but please don't fret about how SW works and why things are free in unlimited quantitie.
SW works. Fact. Yes, if you eat like a piggy until you are stuffed your losses will be slower, but I eat big portions and I lost weight successfully. Don't forget you are restricting other things like bread/cereals/dairy/syns. This is the reason you can have unlimited free foods - but it does say in the book to eat until you are satisfied and not for the sake of it.
I have the biggest jacket potato I can find in the shop, I have a mountain of pasta (eg if the recipe serves 4 it will probably serve 2 of us with a small lunch portion left over!!) - don't worry about it. Don't restrict yourself, just enjoy your food and eat until you are full. That's the only portion control you need on SW!