MetaChat - Why do I weigh less in the morning?

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08 May 2008

Why do I weigh less in the morning? →[More:]I just got a bathroom scale and I'm running amok with it. It turns out you can weigh all sorts of things! Including yourself half a dozen times a day.

So... why am I always 2-4 pounds lighter in the morning? Am I really sweating out 3 pounds of water every night while I sleep? That seems hard to believe- I'd have to wring out my pajamas.

Any ideas?

post by: small_ruminant at: 15:29 | 20 comments

Yes, it's sweat. Plus probably about half a pound of skin that those invisible bed mites nibble off you in the night. They gotta eat, right?

posted by essexjan 08 May | 15:33

I always assumed it was because I ate during the day. Are you weighing yourself right before you go to sleep, and then right after you wake up? If so, that *is* freaky weird.

(I mean, it's freaky weird cool that bodies would do that, not that you're freaky weird.)

posted by occhiblu 08 May | 15:35

Yep, that's why it's important to pick a consistent time to weight yourself. I weight myself in the morning before I eat, when I'm at my lightest :)

I also found out that I sweat out a bunch of weight while I exercise - my post-exercise weight is a few pounds lighter than my daily average.

posted by muddgirl 08 May | 15:36

Combination of perspiration, exhaled water vapour and exhaled carbon dioxide.

The carbon dioxide alone is 900g per day. If you sleep 8 hours that's 300g or 0.7 pounds overnight.

However I woudn't discount the scales being inaccurate. If the temperature in the morning is different, that could cause the readings to be systematically different. Or you might be over-interpreting random changes.

posted by TheophileEscargot 08 May | 15:37

Also, I was reminded from essexjan's link that apparently bodies do get rid of burned-off weight through the breath. Which I find a fascinating, if completely opaque, process.

posted by occhiblu 08 May | 15:38

occhiblu - that's related to a documentary I saw once, where a guy asked some graduating college science majors, "Where does the mass come from such that an acorn can grow into a big oak tree?"

The answer, to the surprise of many students, is that it laregely comes from carbon extracted from CO2 in the atmosphere. So the mass that we breath out of our bodies is breathed in by plants, who convert it into cells and such.

posted by muddgirl 08 May | 15:54

So the mass that we breath out of our bodies is breathed in by plants, who convert it into cells and such.

SO COOL! "Conservation of energy" is one of those very abstract concepts to me, and it's just very very very neat when I can kind of pin it down onto concrete things like that. We are stardust, etc etc.

posted by occhiblu 08 May | 16:03

Wow! Heavy breath!

I don't think it's temperatures because it happens no matter the weather or time of year. (I noticed it before when I went to the gym, too.) And yes, I weigh myself before I go to sleep and right when I get up. No eating, peeing or anything else in between.

Once in a while I stay the same overnight but it's so rare that I always weigh myself a bunch of times before I believe it.

muddgirl, that is really really cool about trees.

posted by small_ruminant 08 May | 16:08

Whoah, that is cool! So those ugly, stunted trees that never seem to grow well are where halitosis goes, I guess?

posted by dg 08 May | 16:10

It's totally normal. Here's a geeky explanation.

In fact, it can drive you nuts if you're on a training or weight loss program and you seem to be bouncing up and down all the time. That's why fitness buffs and doctors and Weight Watchers recommend you weigh yourself at a consistent time of day. I also like morning, before I've eaten anything or started taking in more water -- psychological boost. ;)

posted by Miko 08 May | 16:13

You owe essexjan a coke, Miko!

posted by small_ruminant 08 May | 16:44

Our scale is broken. I don't actually know what I weigh.

posted by jonmc 08 May | 18:25

You're missing out! You can weigh books and chairs and vegetables and guests. I'm entertained.

(Why yes- I DO have patient friends, now that you mention it.)

posted by small_ruminant 08 May | 18:33

And cats! (Hold the cat, find the weight, weigh yourself, subtract your weight from the combined weight of you and the cat. Works much better than trying to get the pissed off cat to stand still on the scale.)

posted by mudpuppie 08 May | 18:35

You're missing out! You can weigh books and chairs and vegetables and guests.

They have a scale at the supermarket for that, s_r. And most of my food has it's wieght already printed on it. Consider my indifference to scales a protest against a weight obsessed society. or something.

posted by jonmc 08 May | 18:39

Now I'm imagining taking my furniture and laundry to the grocery store to weigh in the hanging scales... Nah. Just entertained by a new gadget.

posted by small_ruminant 08 May | 18:50

this brings to mind dersin's solution for finding out the weight of a head.

posted by small_ruminant 08 May | 18:52

You may not know this, but you're suffering from somnambulism and you're riding a 25K circuit on your bike. You think you're sleeping.

Scales¿ Save them for the piano or guitar, the only one who gives a damn what one's weight is, is your GP. Then they'll give you the spiel about too many cokes, snacks or beer...

[I jest] Throw the scale out the window... what good is it.

posted by alicesshoe 08 May | 20:27

Okay- in all honesty I just got it because I started a new medication and I want to see if I gain or lose any weight on it. The book, furniture, and canned goods weigh-ins are actually just perks.

posted by small_ruminant 08 May | 22:57

*Starts hyperventilating*

Am I thinner now?

Those bulimic models are doing it wrong.

posted by qvantamon 09 May | 02:54

← I feel a bit better about things now || He's back! →

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