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What About Water Weight?

July 2, 2009

So, what’s the deal with water weight, anyway? You hear the term all the time in regards to dieting – especially low-carb dieting – and it is usually attached to the word “just” – either with a sneer [as in, “Sure you can lose 5 lbs in the first week, but it’s just water weight”] or with sympathy [as in, “Well, yeah, you gained 2 lbs this week, but I’m sure it’s just water weight].

I’ve said it before, and I’m sure I’ll say it again, “The scale is not your friend.” Not for weekly and certainly not for daily weigh ins. Not unless you KNOW HOW WEIGHT FLUCTUATION REALLY WORKS. Now, that said, I do a weekly weigh in right here on this blog. That is partly for accountability purposes and partly because I want to see what this new way of eating is doing to my body and the scale is one of many measurements I use.

But it is certainly not the only measurement. Once a month I weigh in and break out the tape measure to see how I’m changing dimensionally – and that is the measurement I am really following.

But the fact remains that most people do use a scale on at least a weekly basis if not more frequently and quite often the scale shows alarming fluctuations. Why?

First, lets acknowledge that your body is a complex machine and its various components are in a state of constant flux. Your hormones, your digestive system, muscle growth . . . nothing is ever static. Your body is trying to maintain a delicate balance between vastly differing systems that are all reliant upon one another for life and survival.

IOW Things are constantly changing.

See, your scale does not just measure fat. It measures total weight. And large, seemingly arbitrary jags in weight can almost always be attributed to this thing we call water weight.

The reason so many low-carb diets claim you can drop several pounds in the first week or two is that you can. And that is because carbohydrates (does anyone ever think about the term “hydrate” being part of carbohydrates?) carry about quite a bit of water.

Your body stores carbohydrates in muscle, liver, and fat cells as glycogen. This is not the only thing it does with carbohydrates, but after fuel consumption and before fat storage a good portion of the carbs you eat are stored this way.

Why does your body store glycogen?

It’s basically quick energy. You don’t burn much of it walking a couple miles or slinging weights around, but if you have to sprint, or run/jog long distances, your body burns glycogen. It is also used to keep your brain and other vital organs functioning properly.

But when you reduce the carbs in your diet you reduce your glycogen stores. (Don’t worry about your brain, your body can synthesize proteins from your diet or – in emergencies – from your muscles into glycogen to keep your brain going)

For each gram of glycogen you store you are also storing a little more than 2 grams of water. So for each gram of glycogen you ditch (and you are probably carrying a couple pounds of the stuff) you are also ditching better than two grams of water (so if you ditch 2 lbs of glycogen you end up ditching 4 – 5 lbs of water with it for a net weight loss of 6 – 7 lbs – none of it fat).

Are you with me so far?

Now, as long as you stick to the low carb diet you won’t see that initial loss of 6-7 lbs come back. But throw in a cheat day and it could hop right back on. But if it’s just a cheat “day” (as opposed to a cheat week or something) it could well be gone again before you get back on the scale.

And that water weight is probably what you are seeing when your weight fluctuates. If you weighed 250 lbs one week and 255 the next you haven’t gained 5 lbs of fat.

It still takes a calorie surplus of about 3500 calories to gain just 1 lb of fat. You’d have had to have eaten an extra 17,000 calories that week to have gained 5 lbs of fat and that is above and beyond your normal calories.

I’ve calculated that I need roughly 4000 calories a day to maintain my weight at my current activity level. I would have to eat nearly twice that in one day to gain just one pound of actual fat.

But I only need about 70 grams of carbohydrates to restore my glycogen levels and the water they bring with them. That’s 2 pieces of 6″ whole wheat pita bread, folks. Or 1/2 cup of raisins. Or 2 bananas. Or 1 large potato.

Now, most low-carb diets call for less than 50 grams of carbs per day to maintain ketosis (wherein your body likes to liquify your fat and use it as energy instead of glycogen), but they often allow for as much as 50-100 grams, so you can still store glycogen on these diets – and it can still fluctuate.

You eat eggs and bacon for breakfast, leftover meatloaf for lunch, and a steak with buttered broccoli for dinner one day and then have fruit and nuts for breakfast, a big salad with grilled chicken for lunch, and seared eggplant and portabella mushrooms for dinner the next – guess what. Your water weight is going to yo-yo.

And that’s okay.

So long as you don’t think of it as fat when you step on that scale.

Listen to the scale month to month at best and really get into the habit of using other measurements like body fat %, waist, thigh, and neck measurements in inches, how your clothes fit, how you feel, your blood work from the doctor, etc – let all these things paint your picture of progress.

Not just the bloody scale.


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