6lbs lost in 4 days, a little worried...

Well, I just started a 1300 calorie diet on July 1st, and since then I've maintained without falter eating 1300-1500 calories a day and exercising at least twenty minutes a day (my plan: easy walk three days a week, pilates/core work out four days a week. So far so good on that...). Well, when I weighed in on the first day, I was at 212lbs.  Yesterday, I weighed about 207.5. Today, I weigh a little under 206lbs. So, as such, I'm a little worried about how fast I'm losing weight. Now, I know there could be a few causes for this:

1. I have hyperthyroidism. I think this is a sign I need labwork done to change my tapozole dose. However, usually I'd have other symptoms when it was time to change doses, like irritability and fatique.

2. Its that time of the month (maybe that changes things?).

3. The couple days before I actually joined the site, I was eating between 2100-2300 calories a day and made no effort to go out of my way to exercise.

4. It could be water weight. I am still rather confused about how water weight can fluctuate in some people and not effect other people.

So, long story short: Any advice on this would be greatly appreciated. Is it pretty typical to lose that  much weight when drastically changing your diet? Is this some sort of plataeu? Since I do have a thyroid disorder - caused by Graves Disease, if that helps - I really would rather have healthy steady weight loss than a sudden drop that could seriously mess up my already messed up thyroid. Thank you so much for any help!!

I in no way can give any advice that equates to a medical opinion, but I would only worry if this is a pattern that occurs more consistently than four days.  The most weight loss occurs at the beginning of diets and you have a rather large calorie defecit.  I think water weight is to blame, especially since it is your time of the month.  You retain water and bloat during your period.  I would see if things steady out a bit over the week and if you are still greatly concerned, discuss this with your doctor.  I wouldn't worry too much just yet. 

Since it's only been a week it's probably a combination 2, 3 and 4.

A lot of people loose suddenly when they change diet and most of it's water (you also could have put most of that water weight on the few days before 2 and it comes off after).

If you loose the same next week I'd consider 1 seriously though.

Thanks guys - I'm glad to hear that this is semi-normal. I was thinking the same option as you guys, and I'll probably call for labwork for my thyroid sometime this coming week if the pattern continues.