Just a guess, but could it be down to the resistant starch thing? Having experimented with various forms of potatoes, mash and jackets are out, roasties and chip better (guessing the fat content helps there) the best (for me) are tinned especially if I slice & fry themBut how can it raise the amount of carbs? Let's say you roast 100 grams of swede and boil the same amount and then compare them, would there be more sugar in the roasted ones and if so, where did it come from?