What does it mean when you lose or gain “water weight”. Is it as simple as you’ve drank a lot of water, then pee it out? Does that count as weight?
In: Biology
In essence, you’re more or less correct. Our ability to balance the fluid in our bodies is pretty well-tuned, but it isn’t instantaneous. So depending on fluid intake and output, your weight will vary by up to like 5 pounds depending on how well hydrated you are
I have lost 3 pounds in one workout before. There’s no way I lost 3 pounds in fat; it was primarily sweat
The body stores glycogen in muscles and other areas. When you start a diet or a fast your body releases those glycogen stores and it does so through releasing water through urine. You also lose electrolytes in the process which is why most people feel weak, nauseated, headaches and cramps.
I don’t know all the sciency stuff but you can check out a book called The Complete Guide to Fasting ans it breaks down a lot of the things that happens to the body when you fast. Most diets are really starvation diets which is similar to fasting in a way, so it still applies.
Water weighs about 8.8lbs per gallon. Salt water weighs more. You can drink a bunch of water and retain it, thus being a few pounds heavier. You can then also pee or sweat it otherwise lose water and weigh a few pounds lighter.
This is why you should weigh yourself twice a day of you are trying to lose or gain weight, but do not pay attention to the day to day differences. Look for the weekly and monthly trends.
Also, pay attention to the “weight by water” markings on poultry. Some turkeys around Thanksgiving time have more than half of their weight added by salt water.
“Water weight gain/loss” is not a misnomer per se, but it is slightly misleading.
It’s not about the amount of fluid that’s in your stomach or bladder, it’s about the *extra* fluid that’s in your body tissue, hence the term “fluid retention”.
I emphasize “extra” because it is possible to lose too much fluid. Down this path lies dehydration. As /u/vaper_away mentioned, if you lose 3 pounds in a single workout, that’s not exercise success, that’s just a lot of sweat. You haven’t lost any fat, which is the true goal of weight loss, you’ve lost fluid, which needs to be replenished.
That’s pretty much it, although water weight gain is usually more than excessive hydration, if you consume a lot of salt your body will retain extra water to dilute it. Hormones can cause women to retain water during certain times in their cycles.
It “counts” as weight in that if you step on a scale you will be heavier. Your body naturally retains some water, fighters will often dehydrate themselves to qualify for a lower weight class. That’s water weight they are losing. However, if you are trying to assess how well your diet or muscle building program is working, changes in water weight should be disregarded.
Typically when people refer to losing water weight, it has a lot to do with being sick, and either your illness, or a medication that you’re taking for your illness, or both is making you more dehydrated than usual. There’s a lot of water in your body and that water weighs a substantial amount. If you end up getting dehydrated from an illness or a medication (usually a steroid) then you’ll lose weight, known as water weight.
About 60% of your body weight is literally water. Water is very heavy–about one pound per pint, or one kilo per liter. Assuming that you way somewhere around 155 pounds, or 70 kilograms, that means you have about 90-100 pounds (40-45 kilos) of water in your body. Most of that (about 2/3) is inside your cells. The rest is in the fluid in the “cracks” between your body cells, with a small proportion (about 1/12) making up the liquid part of blood.
Your kidneys and related systems are “designed” to keep the levels of water and all the things dissolved in it pretty constant, since going too far in either direction is bad…if you have too little water, your blood pressure drops and your organs start dying because they aren’t getting nutrients. If you have too much water, it you “puff up” (called edema). If severe, water can leak out of the vessels in your lungs and you start drowning internally (no bueno).
There are lots of ways you lose water–peeing is the biggest, but sweating, the moisture in your breath, and pooping are also big ones. If you’re working out in a very hot environment, you can lose up to *10 liters a day* of water (10 kg or ~22 pounds). Luckily, your body will respond by making you incredibly incredibly thirsty, so assuming you have enough water around you will be okay. Drinking a lot of water will obviously make you gain the weight of that water, but if your kidneys are functioning well you will pee it out quite quickly.
If you’re taking drugs called diuretics that make you pee more, you can lose water too. This is used for patients that have severe edema from their heart not working, as well as to reduce blood pressure in people with hypertension.
Carbohydrates love water (Hydrophilic is the scientific term), so for every gram of carbohydrates you store, you also store 3-4 times their weight in water. So low Carb diets give you an up front weight loss that is greater than you’d expect based purely on calories, since for every pound of carbs you lose, you also lose the water that is stored with them.
Now, since you store an extremely limited amount of energy in carbs (relative to the amount of energy stored as fat), this is pretty short term.
Water is amount is quite dynamic in the body. If you drink a lot of fluids, you will transiently increase your mass, until you lose the water that is (urination, sweat, breathing, etc). If you have an intense cardio workout, you will lose a lot of water due to sweating and breathing. But you will quickly replenish it as you drink again (your body will know it’s missing fluid and it will retain it next time you drink). If you start routinely working out, you will also have long term adaption where your body retains more fluid than it usually does in order to increase blood volume (15% or so if I recall correctly). But when people refer to water weight they’re usually referring to a quick weight loss, too quick to reflect loss of fat tissue. Some people have intense diets where they cut down food drastically to one meal per day and not much of it. Food also contains water, a lot of it, and these people usually lose weight quickly in the beginning, that’s likely water loss because they don’t compensate for the reduced food intake by drinking. And usually when people have diets they also switch to healthier food, and in general healthier food has less salt (like home cooked food vs junk and fast food). Less salt = less water retention, so you lose even more water. That’s why initial weight loss is not indicative of the efficacy of a diet and you need to weight till you reach the plateau phase followed by the ever so slow linear phase before you can judge a given diet.
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