That's what I would do. That way you also see if you have any intolerance to the food, too.

I still have the II book and found on page 95 her explaination why she doesn't want you to go into ketosis. It actually has to do with your insulin levels. Just like you don't want them to get too high, you don't want them to get too low. Without enough insulin your body starts to use up functional and structural biochemicals. She explains that insulin is your "building-up" hormone, while cortisol and adrenaline are your "using-up" hormones. Without the balance you will either gain weight with too much insulin or lose bones, muscle, etc without enough insulin.

In ketosis your insulin levels go too low.