Real vs. fake weight loss

I've been trying to figure out why it is that I can (seemingly) drop six pounds in just over a week.

The day after Christmas? 146.6.

Today? 140.8.

To have a six-pound weight loss, you need to have a calorie deficit of 21,000. Now, I know I've been meal-tracking for a week or so and have gotten some solid exercise done at the gym and skiing. But I haven't created that much of a deficit - more likely, I've created one pound's worth, or 3,500 calories, of deficit.

So I was thinking water weight, and that makes sense given (TMI alert!) that I got my period on Christmas day. Women retain water just before and during menstruation.

But I actually think I was dehydrated during the holidays. At work, I sit with a cute pink water bottle that Danielle gave me and I drink from it all day, and refill it multiple times. At home, I drink Diet Coke, diet iced tea, or nothing. Maybe my body held on to the water, but I still felt thirsty? Is that possible?

If not, what was it? I mean, I guess I should just appreciate it, but I really want to understand how the weight can move that dramatically.

Here's how it broke down over the last week or so. Yeah, I'm a bit nutty about the scale. I always weigh myself first thing in the morning, under the same conditions.

Dec. 26: 146.6
Dec. 27: 146.0
Dec. 28: 143.4
Dec. 29: 143.8
Dec. 30: 143.8
Dec. 31: 142.2
Jan. 1: 142.6
Jan. 2: 141.6
Jan. 3: 140.8

Hmm. Maybe that is reasonable, if the 146 weighings were off for a huge water retention reason, and the rest is weight loss?

I wish I knew. I wish I could measure. Then again, maybe I'm obsessive enough with what I already know.

Anyway, I did a spin class again today. My muscles - especially chest and shoulders - are sore from yesterday's strength training. But that's a good thing!