No you wouldn't need to syn it, unless it's one of the already synned ones
Anything that shows on the SW website as FREE, is Free. No matter how much of it you eat.
However, I would always advise eating the free foods in moderation i.e. potatoes, rice, pasta, yogurts, etc.
Eating too much of these and not enough of the Speed and Protein foods can stall your losses further down the line
Probably a much longer answer than you were looking for so I apologise for my rambling