How much weight would I lose if I lost water weight? What Is Water Weight and How Can You Get Rid of It? After pounding a deep-crust pizza, do you feel like you've been pumped with a tire pump? The good news is that you haven't gained 10 pounds of belly fat overnight. If you wake up to an unpleasant surprise on the scale, you may credit water retention. Here's what water weight is, as well as some tips on how to reduce it. What is the weight of water? To operate, your body needs a lot of water: Water makes up about 50 to 70 percent of your whole body weight. Maintaining your body's temperature, cushioning your joints, and getting rid of waste through perspiration, urine, and feces are all dependent on keeping your body hydrated. The amount of water in your body is mostly determined by your age, gender, and body composition—but what you consume, in particular, might lead you to retain a few extra pounds. Why does your body hold on to so much water? Carbohydrates and sa...