You asked: What is water weight?

Muscle and fat don’t appear overnight, and if you’re hopping on the scale and noticing a big change since yesterday, chances are that it’s just ‘water weight.’ That leads to questions, though: What is water weight, is it necessary and what does it mean? Gabe Neal, MD, family medicine physician and clinical assistant professor at the Texas A&M College of Medicine, explains what your water weight says about your health.

Water in our bodies

Water is the source of life, and many people don’t drink enough of it (the current recommendation is about three liters per day for men and about 2.5 liters per day for women). Being well hydrated benefits most of our health functions, including blood flow, organ function and skin health. On the other hand, being dehydrated can lead to a wide array of problems, including fatigue, nausea, headaches and dizziness.

Water makes up a big part of our body, and it can show up in the numbers. “Most of our weight is water,” Neal said. “It’s the heaviest thing in our body besides our bones, and it is one of the first to go when you start losing weight.”

Water weight is typically the first to go when you begin a calorie-restricted diet. Your body burns through the calories, then dips into your glycogen supply for energy. Glycogen is bound to the body by water, and the process results in the water being released and your pants fitting a bit better.

Also, people who have higher percentages of body fat normally have a lower percentage of water compared to people with lower body fat percentages. For example, someone with 15 percent body fat will have a higher body water percentage than someone with 30 percent body fat.

Apart from higher numbers on the scale, having high percentages of water weight can be a sign of (or lead to) health problems.

Excess water

We want water in our bodies—as long as it’s being used effectively and in the right places. It’s when it starts going into the wrong place that it starts becoming a problem.

“Water, when used efficiently, goes all over our bodies,” Neal said. “We want it to go to our arteries, veins, tissue and cells throughout. However, when it goes to places between the cells and around the fat—an area called the ‘third space’—it becomes a problem.”

Water goes to the third space in the body when there’s an imbalance between the forces that are responsible for pushing the nutrients and water from our blood supply into our cells. The cells eventually become overloaded, and the water cannot go where it is needed anymore. The water then eventually goes into the “third space” beyond the tissue and capillary membranes and into areas like the abdomen and peritoneal cavity.

There are conditions that may cause water to go to this third space, such as inflammation in the abdomen, pancreatitis and pleural effusions.

Daily causes of water retention

More likely than not, retention is due to common daily nuisances that can cause some water weight to be retained but that don’t indicate a health problem. Increased salt intake, even in people who are otherwise healthy, can increase water retention. “From a chemistry standpoint, water follows salt,” Neal said. “If your diet has a lot of sodium, then the water will follow and not go where it’s supposed to.”

Reducing obesity and getting back to a healthy weight will help reduce water weight. Water will more easily store in your body if you are obese, and losing weight will also increase the speed at which water is unnecessarily retained.

Women may notice they retain water leading up to, and during, at certain periods during their menstrual cycle. This occurs because of hormone changes associated with the menstrual cycle that also cause breast tenderness. Both symptoms will typically go away later in the cycle, and diet and exercise can help reduce the excess fluids.

Common causes for water retention

There are other medical conditions that can create an overload of water in the body and especially in the third spacing. The most common reasons are heart failure, an under-active thyroid and venous insufficiency. If thyroid or cardiovascular conditions are a concern in your family history or medical history, let your health care provider know.

“If it’s heart failure, we need to optimize heart function, control blood pressure and prescribe a diuretic to help remove excess water,” Neal said. “There are also thyroid supplements that can help regulate an imbalanced thyroid if that’s the issue.”

If it’s neither of these conditions, the problem may be venous insufficiency, which is a condition where the veins aren’t working properly and a common cause of water retention, particularly in the lower legs. “The common sign of venous insufficiency is swelling in the legs and feet,” Neal said. “This is not normal and can cause discomfort, skin darkening and possibly lead to infection.”

You can decrease your chances for venous insufficiency by keeping a healthy body weight, not smoking and avoiding prolonged sitting and standing. Compression stockings can help reduce the amount of swelling in the affected limbs by promoting proper blood flow from the veins to the heart.

Talking to your health care provider

Overall, water weight is normal and drinking a lot of water won’t lead to health problems or problems on your bathroom scale. In fact, being dehydrated can cause your body to store water to compensate, which can lead to more water weight.

However, when fluids in your body begin to work inefficiently, then you need to talk to your primary health care provider.

“If you begin to notice swelling where there hasn’t been any swelling, or notice a sharp increase in weight, you should talk to your health care provider,” Neal said. “Also talk to your provider about how much water you’re drinking in a day and if you think your water intake and retention are affecting your health.”