Lab HELP!!!! PULEASEEE!!?

If you have a dialysis bag (no leakage) with a starch solution in it, why does the weight of the dialysis bag slightly change when you put that bag in a beaker filled with water and a few drops of iodine? ( I already know that iodine molecules can bind to starch but is that the reason why the weight change? Does iodine change the starches m?)