I started my period the day before I started LT. I don't have bad period pains or anything so I don't need to take any medicines at that time, what did you take? I know paracetamol is allowed and I have taken a tablet a couple of times especially during the first week when I had a couple of headaches. I doubt the tiniest bit of cereal on your first day will make any difference to your weight loss for the first week. On a side note when I'm on my period it doesn't seem to make any difference to my loss for that week but I know others on here have different experiences. Best wishes for Day 2. Keep strong. I found the first week very tough.
BM