What is water weight? Water weight is fluid retention. It is when your body holds on to the water in your body. This can cause you to get bloated, and see a higher number on the scale.
Why does this happen? This can happen for many reasons. Increased sodium intake, too many processed foods, not getting enough protein, not drinking enough water.
Not drinking enough water? The more water you drink the less water your body will retain. This is because when you drink a lot of water your body signals the organs that it is okay to let go of some of the water.
How to get rid of water weight? By drinking more water, cutting out processed and high sodium foods, sweating, cutting carbs.
Cutting carbs- although cutting carbs can help you lose water weight this will not help you lose fat. This is also not healthy. Many fad diets promise large amounts of weight loss in a small amount of time by drastically cutting carbs, however this weight will be gained back very quickly because it is not actually fat loss. This has to do with glycogen, and you can learn more about this here and here.
Water weight and fat are very different. This is why you should not freak out if you see a higher number on the scale. Fat is burned by being active and operating at a calorie deficit.
So in conclusion if you see a high number of gain or loss on the scale in a rapid amount of time it is most likely water weight. I highly recommend that you watch this video.
*** Remember that 2 liters of water is going to weigh 2 kg (4.4lbs). If you drink all the water you’re supposed to, your weight WILL fluctuate throughout the day ***
This is another reason not to think about the scale!
info from here