5.2lbs gone in 5 days! What the heck?

How can I be losing so much so fast? I lost 1.4 in one day! And it is TTOTM. I used to lose that much in a week! My goal was to lose 8.6 by the end of December and as of today I have 1.4 left to lose in the next 15 days!

I haven't really changed things around that much. I'm still eating my 1500-1600 calories every day. My fibre is always perfect. Fat is below 25% of my calories. My salt intake is always below 2400mg.

The only things that have changed in the past week that I can think of are:

• I have cut back on exercise from 60min every day to 60min 3x/week due to an old ankle injury acting up. All I have ever done is cardio (walking, elliptical and aerobics). Could I be losing all my muscle?
• I've been drinking 8-10 cups of water every day, whereas before it was about 4-5 cups a day. Maybe I am just losing water weight? But 1lb a day?
• 10 days ago I started taking Tonalin CLA (4,000mg/day) as my doctor recommended it for my hypothyroid condition and cholesterol. Could the CLA be taking effect?

I know it's nice to lose weight, but I am worried that it is not safe, it all might come piling back on at once or I will get extremely flabby from losing it so fast. I feel fine except that I could sleep forever, but once I'm up I seem to have lots of energy.

Anyone have any ideas? Should I be worried?

EDIT: Studies (Journal of Nutrition; International Journal of Obesity; Lipids) have shown that CLA (Conjugated Linoleic Acid) increases metabolic rates, decreases abdominal fat, enhances muscle growth (muscle burns fat), lowers cholesterol, and lowers insulin resistance.

That's interesting. You know, the same thing happened to me about a month ago- while I was on my TOM too...I figured that all my hard work just finally caught up!

I seriously doubt it was the CLA, and I find it strange that your doctor asked you to take an OTC supplement which is unproven by the FDA for a legitimate medical condition (hypothyroidism). I actually researched CLA myself a few weeks ago, and I found several actual trials that said CLA did nothing over placebo. Through my own research, I've found that the only non-prescription things that work for weight loss are caffeine, green tea and ephedra (which is actually illegal now).

The water was probably a good part of it.  I also find that when I've been working out everyday and hit a bit of a plateau, cutting back usually drops the weight off.

And I wouldn't worry unless you continue to lose weight at that pace.

It very well could be water weight. if you haven't been hydrated and you start drinking more, initially you could see weight coming off very fast. I did some reading about this when I started drinking more water and it seemed like I was running to the bathroom constantly. Your body has a threshold at which it is fully hydrated and will start to let go of excess fluid that it has stored if you are not drinking enough. I really doubt it is the CLA - that tends to cause body composition changes but little actual weight loss, if you look at the studies. Also, you should be careful because some of the research on CLA shows that the kind you take in capsules is a form of trans fat and will raise triglycerides and bad cholesterol, although it may have a favorable effect on body fat. It's safer to get CLA naturally. Some sources are raw milk cheeses (from grass fed cows) and grass fed beef.

I've seen similar things happen when cutting back on strength training. I think it could be related to the water that the muscles retain while re-building. After thanksgiving I lost 7 lbs in 6 days, Sun to Fri. I attributed that to water weight from flying (I can get bloated from the altitude) and not being able to control sodium levels. I've bounced back a little (dang it!) from the low that got generated by that effect. Didn't regain it all when I re-started my regular eating and workout plan.

Women usually range in weight up to ten pounds during the month. It's due to the menstrual cycle and water weight. I believe it's a combination of the water and the time of month. Seems like what you are doing is really healthy, so keep it up. If you are still underweight in a month, then add some calories to your diet.

=)