Ms Motivated - are you sure that you have been drinking plenty because dehydration can give you headaches? You may be feeling hungry after your soup because eating triggered your'hungry switch', which carorees has talked about elsewhere in the forum. That is why many of us prefer not to eat at all until the evening when we splurge all 500 calories on one good meal!
To everyone else fasting today - I hope it's going well for you! I'm into the home straight now, before my 500c feast, because I think my husband, who is also fasting today, will be needing food before 7pm tonight!