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Water Weight

March 30, 2009

During the early days of a diet, it’s common to lose a fair amount of weight in a short period of time. Depending on the type of diet, anywhere from 3-8lbs is common. Most people know that this is ‘just’ water weight, but do they know what exactly water weight is? Our bodies don’t respond to a calorie deficit by dehydrating do they?

You’ve probably heard someone likening body fat to a savings account. We store energy in the form of triglycerides (because they’re the most energy dense of the macronutrients) so that when food is scarce or we are called upon to use a lot of energy, we can have a source of energy without having to find food. But the body also has a ‘fast cash’ option we can use for sudden emergencies. This fast cash is glycogen and it’s stored in the liver and skeletal muscles.

Now all the uses and the metabolism of glycogen are very interesting and I’ll include some links for the ultra-dorky like myself. However, for the purposes of this post what you need to know is that for every gram of glycogen stored in your body, you’ll also store 2-3 grams of water. Now, one number for the average amount of glycogen stores in a healthy person is around 400g so, on average, someone might have upwards of 1200g of water stored alongside it. And there is some evidence, although a quick search didn’t get anything definitive, that heavier people store progressively more glycogen as weight goes up.

So you decide to go on a diet, you drop you rcalories below maintenance and your body needs to make up that energy from somewhere. Since glycogen is a form of glucose, it’s more readily available for use and your body will go through much of its stores. Again though, for every gram of glycogen you use, you’ll ‘lose’ 2-3 grams of water alongside it. If someone uses 400g of glycogen, this can show up on the scale as 3+ pounds lost pretty quickly.

This is why low-carb diets have such a drastic effect on people’s weight at first; if you’re taking in very few carbs, you’re body will have to use even more glycogen and more quickly. This is also the way some low-carb gurus scare people into believing they can never ever ever ever eat carbs again. “If you eat carbs, all the weight will come rushing back!!!” And sure enough, your scale will show a gain of a few pounds if you go back to eating a more carb-heavy diet, but that gain is mostly water and any fat you’ve lost will only come back if you consistently eat above your maintenance level.

Is this a bad thing?

Water weight gets a bad rep as being ‘fake’ weight loss. This is partially deserved as the same glycogen you depleted last week can come back if you have a day where you consume a lot more carbohydrates than usual. When the glycogen is stored it brings along 2 or 3 of its watery friends with it and voila your scale shows a gain of several pounds after only one day and omg!!!!!!! I’m never going to lose weight and I should just starve myself!!!

I think the overreaction to these weight fluctuations is mainly just ignorance. If you don’t understand that it is nearly impossible to gain a couple of pounds of fat in a day and you don’t understand the basics of glycogen storage, you’re much much much more likely to panic the day after you went to that fabulous Italian restaurant than if you understand what’s happening. Of course, it takes away some of the joy a lot of people get during the initial phase of their diet when it seems like their weight is just racing down, but I think that’s a small price to pay in order to avoid all the panic so many dieters seem to experience when they have a sudden weight fluctuation.

However, I also think there’s nothing wrong with being happy with that initial weight loss. At the very least, it shows that you are burning some of your body’s energy stores. So long as people understand what is actually happening, I don’t see it as a big problem. Especially if someone is looking at weight loss over months and years. Mainly, I think the things to keep in mind are:

– Fat loss is what people are after.
– A pound of body fat has ~3500 calories.
– Therefore you must have a calorie surplus of at least 3500 calories to gain a pound of fat
– And you must amass a calorie deficit of at least 3500 calories to lose a pound of fat.

If you understand that and you have some basic idea of how many calories you actually need, then you can avoid the panic brought on by fluctuations in water weight for the most part.

References and other articles:
Glycogen Storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition.
Water Weight vs Fat Weight
Glycogen metabolism
Body weight and glycogen depletion.
Quick weight loss and glycogen.

10 Comments leave one →
  1. meerkat permalink
    March 30, 2009 4:26 am

    any fat you’ve lost will only come back if you consistently eat above your maintenance level.

    Wow, I guess all those failed dieters were just pigging the hell out! (No offense to actual pigs intended. I can’t think of a verb for this that doesn’t insult pigs.)

    • March 30, 2009 4:42 am

      Why would someone have to “pig out” in order to eat above maintenance? If anything I thought the idea was that dieting might lower ones metabolism enough to make eating above maintenance easy?

  2. March 30, 2009 6:30 am

    I think it’s very easy to eat above maintenance, even when trying to not “pig out”. I think for those of us who tend towards overweight but don’t want to be, we need to be very conscientious, especially eating at restaurants, even healthy ones. Even whole foods. Portion sizes can be deceiving. And as someone who cooks, and often tries to copy things I like, it takes a LOT of butter to make things taste like many of these yummy foods that look so healthy.

    I have never had this fast weight loss due to glycogen/water. Instead, I seem to work my ass off for months before the scale budges at all. The scale isn’t always so useful to me, I weigh every day, but don’t take the number personally.

    • March 30, 2009 8:46 am

      It’s really easy for me to eat several hundred calories per day more than I planned. That’s part of what that “This is not why you’re fat” post was about: I don’t have to eat that much more in order to maintain a higher weight.

      You know, I’ll have to find the link, but I was reading about the tendency in women for weight to kind of “whoosh” off after standing still for a time. One theory is that, for some reason, as fat cells empty, they sometimes fill with water for a time so even though you’re (general you) are losing fat, it doesn’t show up until you drop the water. I know that it kind of matches my pattern of weight loss.

  3. March 31, 2009 5:20 am

    I think for the most part, our metabolisms adjust for uneven calories. I’m not sure that an extra two or three hundred calories a day will cause serious weight gain. It probably prevents weight loss. Constant overeating can tip the balance, I suppose. I’m going to have to think about this.

    • March 31, 2009 5:32 am

      There might be a difference in terms of what one has to eat the gain/lose and how you can eat to maintain. Like you need a little more/less in order to overcome the body’s tendency to adjust to intake. I really don’t know. The research is really just so limited.

  4. March 31, 2009 12:49 pm

    Another fantastic and important post. “Panic” is exactly where I was this morning and where I’m trying to dig out from. I’m printing this one out for next time. Thanks for what you’re doing here. You are making a real difference. xo

    • April 1, 2009 8:10 am

      Glad to be of help. 🙂

      Honestly, I write this as much for me as anyone else. If I have a particularly carb-heavy day and my weight goes up, it can be easy to fall into “See, I was bad and now I’ve gained 2 pounds because of it” thought pattern. I just have to keep reminding myself that this stuff isn’t magic and remind myself to stay rational about it all.

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