What is the medical reason to not allow you to donate solely based on your weight? Is it too dangerous for you?
Well, since the liver filters out the toxins in your blood, produces bile to help digest fat, etc, if you weigh more (OP said she had to lose 60 lbs?) I'm assuming you need a bigger liver to handle the extra body mass/blood volume/fat digestion so taking a chunk off wouldn't be all that helpful to the donor...