Here’s a pretty familiar scenario for anyone freshly embarking on a new weight management plan: you’ve just started, you’re excited/nervous, you’re prepared. You’ve consciously adhered to the rules of your program for two weeks, de-ribboned chicken and chopped enough veggies for a V8 commercial, and when you finally weigh yourself your eyes practically pop with cartoonish surprise. Who knew that the scale could dip so far south, with only a few weeks of your effort? This is amazing. You hear the Rocky soundtrack playing at some faint distance.
And just as quickly as the euphoria kicked in, the record screeches to an abrupt halt. You hear a peculiar term tossed, “water weight,” and it sounds dampening to your ears, sounds like being handed the wrong envelope at the Oscars. What’s water weight? What does it mean that “I lost so much weight initially due to loss of water weight?” “Why had I been storing so much water weight?” “Where had I been storing so much water weight?”
Last time you checked, you’re no camel. 
At first it may feel a little disappointing: “after all that hard work, it wasn’t entirely fat I lost, but also water?” you wonder. Don’t feel discouraged! It happens for everyone, and it’s kind of you body’s equivalent of shucking off slippers for sneakers, gearing up to get-set go.
After the brief disappointment, you’re might feel a little confused. “Why is my body behaving like a human Capri-Sun now that I’ve started this new weight management program?” That’s a great question, and one whose answer appears a little tricky on the surface, because there’s a little chemistry involved. But the chemistry is in fact pretty straightforward, and I’m going to try to tell the story of how and why this works.
By now, you’re probably familiar with a collection of words that sound like syllable salad: “carbohydrate,” “glycogen,” “anabolism,” “catabolism,” “lipid.” They’re important here, but don’t get bogged down by them. Carbohydrates are just sugars, and when you comsume a lot of them they’ll string together into glycogen (if a carbohydrate is a single letter, then a glycogen is like a word.) The reason why your body makes glycogen is to store sugar for energy — and strategically, there’s plenty of glycogen located near your muscles, so that our ancestors could run away from mammoths/tigers and so you can run to Hamilton on a treadmill. Your body, however, can only store so much glycogen, and if there are too many carbohydrates lying around (think of them as the extra letters in Scrabble that no one but the makers of dictionaries can use) then our bodies store those sugars as fats. Fats, like glycogen, are also large storage molecules. They’re a lot easier to spell and a lot trickier to get rid of.
When you begin losing weight, your body starts by burning its stores of glycogen. And at this point, you may notice a drop in the scale — and this initial drop is not a loss of fat, but of water. Why? As you know, glycogen is a storage molecule. You can think of it as a large box made of carbohydrates, filled with carbohydrates. And linked to every carbohydrate are molecules of water. It’s where the “-hydrate” part of carbohydrate comes from. If it’s easier, you can think of water molecules as the packing peanuts that cushion stored sugars. So when those sugars in glycogen begin to break down, the water makes a run for it too. This water, which normally hangs out in the tissue between your cells, makes a quiet withdrawal from your weight balance and that’s the last you’ll hear of it.
To give you a little perspective: for every gram of carbohydrate stored by your body, there are 3-4 grams of water stored for company. So imagine this! If you eat a baked potato with dinner, which is generally 37 grams of carbohydrate, you’ll also store 130 grams of water. 130 grams of water is equal to roughly 5 ounces, which is half a pound! If your body were to break down those stored sugars, it would say sayonara to the water too, which is why when you lose your glycogen stores, you lose weight in the form of hydration.
Losing water weight is entirely expected and should not, in any way, flag the optimism and conviction with which you begin your weight management program. Our bodies are curious sacks of molecules. Just keep calm and camel on.
