All I have to offer is hearsay--but I will, anyway I saw a woman at my health food store buying them, and being such a nosy person, I asked her about them. She is diabetic, not LC, but I figure that means she has a lot more to lose than me. She said she takes them for special occaisions, not daily use, and she monitors her blood sugar with real blood (yikes!) not the ketone test strips, and they work for up to +/- 50g carbs (for her).