Where does weight go when you lose it?

This may seem like a funny topic for a blog on climate change, probably because it is a funny topic for a blog on climate change.  But it does have some relevance that I'll tease out before too long.  I chose the topic partly because it 'tis the season to gain weight and mostly because I think it will get the gears in your brain spinning in a different direction.

If you lose weight, where does it go?  What does that lost weight become?  What is that fat the raw material for?

Stop and think about it, and come up with some tentative answers before reading further.

You know I'll wait.

See?  I'm waiting.

If you're like most people I've talked to about this, you assume you sweat it out.  Or maybe that it goes off as poop and pee.  (I hope I'm not being too vulgar for my readership!)

That's a bit of the answer, but just a bit, at least in terms of the stuff that stays gone.  None of that describes what most of the weight becomes.  If you're a regular reader here, you may be making the correct connection to a more Christmassy post a couple of weeks ago.

Indeed many people include things that make them sweat as part of their weight loss regimen.  And, typically, they drink plenty of water along with those efforts, so, that's largely a wash.  When you lose weight, you don't really sweat most of it out.  And, if you're looking for some way around the basic principle that to lose weight you need to burn more calories than you consume, I can't help you.  Sorry.

Have you picked up on where this is going yet?

Another aspect of those things that make you sweat is that they also make you breathe hard.  Most of the weight you lose is turned into carbon dioxide.(!)  Weight loss is something like photosynthesis in reverse.  Instead of taking in carbon dioxide and turning it into the hydrocarbons that make up the mass of a plant, you're taking the carbohydrates that make up the mass of you and turning them into carbon dioxide.  It's actually similar to burning fuel, but fortunately respiration is different from combustion, or I don't think many people would intentionally lose weight.

I'm simplifying quite a bit here.  If you want more details, here's one good place to look.

Sorry, this doesn't provide an eco-friendly excuse to keep carrying that extra weight around.  If you lose that weight, it will indeed turn into carbon dioxide, and, as with gasoline, the emitted carbon dioxide will weigh about three times as much as the weight you lost.

But you'll be emitting less CO2 on a daily basis, and hopefully that addition to the atmosphere (from your weight loss) is a one time deal.  So, every time you get in your car or on airplane, there's less of you for that vehicle to lug around so it will use a little less fuel and emit a little less carbon dioxide.  And you'll emit a little less directly.

You're also likely to be eating less and the carbon footprint of food is large.

So, if you're a tubbo like me and the majority of Americans, here's another reason to shed some pounds: It's good for the climate.

And, hey, some things that make you breathe hard are kind of fun.

Epilogue:
In terms of reductions of carbon emissions, your own weight loss is really pretty small.

This post is more important for building a deeper understanding of the Earth as a system of systems, and especially for thinking about the carbon cycle.  I'm of the opinion that if you don't understand the Earth from a systems perspective, you can't really have more than a superficial understanding of climate change.  It's okay if you don't have that kind of understanding now.  I thought about following that up with a snide remark that it's the American way, but it's not at all unique to Americans.

I have a deeper understanding of this stuff than most folks because it's been central to my work for more than 20 years.  I assure you if you work on it, you can get up to speed a lot faster than I did!  (And hopefully I can help!)