I've been noticing lately that my clothes are looser and I can fit into some things that I haven't worn since before this last pregnancy (baby girl is 4 month old today!). This has got me wondering, where does weight go when you lose it? I tried to logic it out: fat is made up of calories, which is really just a measurement of energy, which is neither created nor destroyed...so...hmmm. It must go somewhere, right? I've never really thought about this before, but suddenly I was obsessed with solving this mystery so I did a little internet sleuthing at ask.com.
By the way, please don't consider any of this to be scientific fact, just a report of what I read while researching. Someone actually asked the inevitable, "When you lose weight do you get rid of it by pooing?" I must admit I had considered this hypothesis myself, but the answer given was "No." I guess if that were the case we could just take laxatives and have permanent weight loss.
Here's the deal. In a nutshell, when you eat fewer calories than you burn, your body turns fat into energy for a series of metabolic processes involving your liver, kidney and muscle. Then, these components are further broken down to provide energy for your body. The heat generated by these processes helps regulate body temperature and the waste products of these processes are water and carbon dioxide. (If that's true, of course, because this was on the internet afterall.)
So you pee it out, sweat it out, and exhale it out. But the process also starts with that calorie deficit--burning off more calories than you eat. Well, this is less glamorous or magical than I had imagined, but it does reinforce for me the efforts i have been making. Please feel free to do your own research and share it here. I'd love to see if there are any other explanations and what they are, but my toddler just woke up from his nap and so my research time must come to an end. In the meantime, I'll be peeing, sweating and exhaling myself away!