Are You Lightest In The Morning?

[Applause] So recently a friend of mine says to me, “Derek, you know you're heaviest at night before you go to bed and lightest in the morning when you wake up."

Okay, but that doesn't really seem to make sense.

“Of course it does. Overnight, you're not eating anything for like 8 hours, but you're still burning calories, so of course you'll be lightest in the morning.”

Yeah, but where's the mass going? Like how are you actually losing particles?

“You can't argue with me. I've weighed myself at night and the next morning, and I know it's true.”

Is that after you went to the toilet?

“No, I told you that has nothing to do with it.”

Why do you have to disagree with everything that anyone says? You just like arguing.

“It's not that I like arguing. It's just that your statement seems implausible. I need some kind of mechanism that would explain how you could be heaviest at night and then lightest by the morning.”

Why don't you Google it?

“Okay, so I Googled it and the results were a little bit disturbing. I'll be 3 to 5 lbs heavier during the nighttime hours, and when I wake up the next morning, I'm back down 5 lb less. I usually weigh myself in the morning; I'm anywhere from 3 to 5 lb lighter.”

Odd, an empty body weighs less than a full one. The force of gravity also can weigh a person down.

“Really? Internet? This is what we're coming to?”

But these are just people posting on forums. Maybe people out on the street are different, so I'm going to go find some people in Perth and see what they say.

But what time of day do you weigh the most?

“Oh, what do you reckon?”

I suppose evening time when eating too much.

“Night time, yeah. Night time, night time, night time, like just before you go to bed?”

Yeah, I'd say that as well. And you're at your lightest in the morning when you wake up?

“Well, you're lightest when you first get out of bed.”

So obviously, if you keep on eating and drinking during the day, you know, I can prove it because I'm one of these sort of people that weigh myself. I weigh myself every single morning of my life, and I'm always licensed in the morning.

When are you the lightest?

“First thing when you wake up.”

Just right when you wake up?

“Yeah, you hop out of bed. Yeah, you are a light man.”

Yeah, of course! The best way to settle this is with an experiment. So every night before I go to bed, I will weigh myself, and in the morning, before I go to the bathroom, I will weigh myself again.

Now, in any scientific experiment, it's pretty important to control your variables. So every time I go for my weigh-in, I'm wearing these exact clothes. I know, pretty snazzy, right? The hotel staff here have graciously allowed me to use their scale, but they told me I can't take it to my room, so I need to do the weigh-ins at the concierge.

I'm going down for my first weigh-in Sunday night; we'll see what my weight is right now at 1:07 a.m.

All right, so 72.1 kg. Where does the mass go while you're sleeping? Like, how do you lose weight while you're sleeping?

“I think it evaporates.”

She sweats a lot.

“I consider digesting it all, so it's kind of probably compressed and out.”

But that's true, where does it go?

“Burning, or we're burning it, using it up, whatever. Burning carbohydrates.”

Okay, so where does the matter actually go? Where does the weight actually go?

“It's transferred as energy that your body uses as you want, like science stuff like ATP.”

Are you saying that we're converting matter into energy?

“Yes, that's one way of – is that what's happening? Rid of it? It uses up the matter?”

Yeah, so your matter is disappearing from inside you?

“Yeah, that's my question. Everything you put into you doesn't all come out the other end as well?”

So your body uses – so where does it come out?

“What uses certain parts of it to sustain you and let you live.”

All right, so it doesn't come out of you?

“Not all of it.”

It's Monday morning. I've just got up. I need to go to the bathroom, so before I do that, I'm going to go down for my weigh-in.

Level three, hello. Last night I weighed 72.1 kg; let's see what I weigh in the morning.

71.9 kg.

Say, 9.25 kg.

I'm not really surprised my mass has only changed by about 150 g; it doesn’t really surprise me, but yeah, I don’t think it’s backing up my friend's theory.

So we'll have to do this a few more times to make sure that these results are valid.

It's a difference of about 0.25 kg, 250 g.

72.05 kg. That's a loss of about 300 g.

So it looks like every night you lose about 250 g, which is pretty similar to the amount that I've been losing every day this week.

So how do you actually lose weight as you sleep?

“Well, every night this week, I seem to lose about 250 g. I think about 150 g of that was water loss through sweating and breathing out water vapor. So where is the other 100 g going?”

Well, every time you breathe in, you're breathing about 500 mL of air, but only about a fifth of that is oxygen.

Now, 3/4 of that oxygen you'll just breathe out again, but one quarter of it gets replaced with carbon dioxide.

Now, carbon dioxide compared to oxygen has the extra mass of carbon on every molecule, and the mass of carbon released in every breath is about 1/100 of a gram.

I know that doesn't sound like a lot, but if you add it up – 16 breaths a minute over 8 hours, it adds up to about 100 g.

Every time you breathe out, you're losing weight because…

“No, come on! I've never heard of that before.”

Then I don't know; people don't talk about it. People don't think about it.

'Cause I think a lot of people think that matter can be converted to energy, that you can take stuff, and then it goes away somehow in the metabolic process.

In that energy process, my point is the atoms are still there. The matter is still there. You need to get rid of it somehow, and some of it is breathed out.

So people were right when they said that you are burning calories, and that's causing you to become lighter; they just didn't think about the exhaust, the water vapor and the carbon dioxide that you breathe out.

So it may be the case that you're heaviest at night and lightest in the morning, but I think the real truth of the matter is you're heaviest after your biggest meal and lightest after you've gone to the bathroom.

It's after lunch on Thursday, so let's see what difference a big meal makes.

I was 71.1 kg; I'm now 72.5 kg. Nearly added a kilo and a half.

My lunch was nearly a kilo and a half, so this morning when I woke up, I was 72.1 kg, but now I've gone to the bathroom, so I'd like to see what difference that makes.

70.6 kg.

That is a lot of mass that I've lost. What is that, like 1.5 kg?

“1.5 kg? That's a lot of mass.”