I know it's been a while since your post, but I hope you are sticking with it. Yes, I've noticed that days leading up to my period tend to be frustrating due to small gains or sustaining even with "safe" foods. I think it is best to just stick to "safe" food days, make sure you are getting plenty of water, and not worry too much. When you are done with your period you can return to testing. I find it's less stressful or frustrating. You can learn a lot about your body as you move through the plan, and then you will become an expert at reading your body and what it does/doesn't need. I wish you lots of success.