The way I believe it works is that the bad seed oils combined with the flours and industrially-produced foods combined with a sedentary lifestyle destroy your insulin sensitivity. You can restore it with a combination of low carbohydrate, nutrient dense real foods and Primal-style exercise (lift heavy things, sprint once in a while, move slowly often and play). Once it is restored, you can eat all the carbohydrate-rich vegetables and fruits you want because the lifting heavy and the sprinting will pretty much demand it and you'll have gained the ability to use it. This might not be true for people who are diabetic and not able to reverse it with diet or for people with other reasons for consuming low carb indefinitely.
If you were never broken to begin with, then really the whole low carb step is probably not necessary unless you just like that food better or just feel happier eating that way.
Female, 5'3", 50, Max squat: 202.5lbs. Max deadlift: 225 x 3.