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
Body weight and glycogen depletion.
Quick weight loss and glycogen.