Water weight gets a bad rap for making people feel puffy and bloated. For many of us, it’s the go-to suspect when our pants won’t zip. As a result, you may be wondering where water weight comes from and how to get rid of it.
Before we dive into safe ways to lose water weight, health and nutrition experts who spoke with WeightWatchers® want you to know an important fact: day-to-day fluctuations in water weight are often totally normal and nothing you need to 'fix'. Sometimes you might not even notice changes in water weight. As we'll explore in a second, water is involved in how the body stores and uses energy.
That aside, certain factors can cause the body to retain more fluid than usual. The official term for the swelling or puffiness you may experience is oedema, which can be mild or pronounced.
Keep reading to learn more about the sources of water weight, some common reasons for fluid retention, what water weight means for health and ways to lose excess water weight safely.
What is water weight?
At some point you may have heard that water makes up 50 to 60% of the human body. Technically, all that water is 'water weight'. But popular usage really refers to the measure of water that fluctuates with diet, lifestyle and other everyday factors—not the H2O bound up in brain tissue, per se. “Water weight is not indicative of your true body weight,” says Dr. Paakhi Srivastava, PhD, a researcher for weight, eating and lifestyle science. “It’s excess water getting stored in your tissue and blood vessels, not muscle or fat.”
Diet plays a big role in water weight, sometimes by design, says Lauren Harris-Pincus, a registered dietitian and nutritionist. Every time you eat carbohydrates, for instance your body breaks them down into glucose, also known as blood sugar. Some glucose gets used right away as a source of energy to power organs, tissues and cells. But some gets stored as glycogen - a backup energy source housed in the muscles and liver. That’s where water comes in; the body bundles glycogen with water at a ratio of about 1:3. In other words, Harris-Pincus says, “each gram of glycogen is stored with roughly 3 grams of water.”
That’s one reason you may feel a bit bloated after consuming carbohydrates. It also helps explain why some people on calorie-restricted eating plans lose kilos rapidly in their early days of their diets. “When your body starts using up your glycogen stores for energy, you lose a lot of water weight with it,” Harris-Pincus explains. How much glycogen your body can hold depends on how much muscle you have, among other things; 300 to 860 grams is typical.
Even if you’re not cutting calories, the body’s everyday use and storage of glycogen (stored energy) almost inevitably causes water weight to go up and down. “Over a week, it’s normal to fluctuate 1 to 1.5kg,” Dr. Srivastava says. While water retention sometimes can be a symptom of a serious health issue (more on that below), it’s usually a harmless phenomenon, she continues—unlike, say, gaining excess abdominal fat, which carries health risks.
Small fluctuations in water weight aren’t always noticeable. But some days, you might wonder whether your jeans are suddenly snug due to water weight or actual weight gain. Dr. Srivastava says a distinguishing clue is that water weight often shows up in the body’s extremities—think hands, feet and ankles. Firmly pressing a finger on a bloated area might tell you more, too. If an indentation lingers in your skin after you release the pressure, Dr. Srivastava says, it’s probably a sign of water weight. Finally, unlike weight gain—which tends to be more gradual after a period of eating more calories than the body needs—water weight can literally appear overnight.
Carbs don’t tell the complete story of water weight—far from it. Read on to learn about some other variables, such as medications and hormonal activity, that can cause the body to retain water, along with healthy ways to beat bloat if it’s bothering you.
What causes water weight?
Factors such as hormonal activity, food choices and medications can contribute to fluid retention in the body. Here are some common contributors:
- High sodium (salt) intake: If you've ever crunched through a bucket of popcorn at the movies, you've probably noticed that salty foods leave you thirsty. As a result, those salty meals and snacks may also make you feel bloated. According to a 2017 review of studies, extra water intake doesn’t necessarily lead to more urine output right away. Rather than making you pee, water hangs out in the body to dilute the sodium concentration in blood.
- Menstrual cycle: People who menstruate experience hormonal shifts throughout the month that can cause water weight to go up and down, says Natalie Rizzo, RD, a sports dietitian. Many women feel most bloated right when their period hits—water retention tends to peak on day 1, a 2011 study found. More research is needed to figure out why, but the hormones progesterone and aldosterone may play a role. In the days leading up to menstruation, progesterone levels rise, setting off an increase in aldosterone. Previous research has found a correlation between higher levels of aldosterone and fluid retention.
- Dehydration: Odd as it may sound, but being parched can lead to water retention. “You would think that being dehydrated is a good way to reduce water weight, but it actually does the opposite,” Dr. Srivastava says. “When you’re dehydrated, your sodium-to-water ratio becomes unbalanced and your body will hold on to any fluids it can until that balance is restored.” In a move called renal conservation, the kidneys reduce urine output to keep water in your system.
- Certain medications: Almost every drug comes with a long list of potential side effects. Medications that may cause water retention by affecting kidney function include over-the-counter NSAIDs (Nonsteroidal anti-inflammatory drugs, such as aspirin and ibuprofen), as well as prescription corticosteroids, which reduce inflammation for conditions such as arthritis and asthma. Chat with your doctor if water retention is bothering you and you suspect your medication is contributing to the issue. A different medication or lower dose might bring relief.
Health conditions that can cause water weight
In some cases, oedema is a sign of a more serious health concern, Dr. Srivastava says. For example, swelling in the lower body or abdomen can be a sign of heart failure, as underlying circulatory issues can cause fluid to build up in tissues. Fluid retention is commonly seen with chronic kidney disease as well, given the kidneys’ critical role in processing sodium and water. “If you notice your puffiness has lasted for an entire week or longer, or if there are other symptoms—the puffy areas are tender, the skin looks shiny, or if it’s accompanied by stiffness in the nearby joints—those are signs you need to see a doctor,” Dr. Srivastava says.
5 ways to lose water weight
Once you understand how excess water weight occurs, controlling it is often possible with simple lifestyle measures, Dr. Srivastava says. Here are some tips to consider:
Watch salt intake
Given that too much sodium increases fluid volume in the body, reducing salt in your diet may be helpful for dropping excess water weight. The Australian and New Zealand governments recommend adults eat around 2,000 mg of sodium per day (the amount in about 1 teaspoon of table salt). “Most of the salt you get is actually from processed foods, not out of a salt shaker,” Harris-Pincus says. Cooking meals from scratch is one way to keep tabs on how much sodium you’re getting. Another is to read nutrition labels on packaged items so you can make informed decisions. Foods that contain less than 120mg of sodium per 100g are considered low in sodium; those that contain 400mg of sodium per 100g or more are considered high in sodium.
Stay hydrated
Beating thirst-induced bloat is as simple as keeping a full water bottle handy, Rizzo says. Because there’s no hard and fast formula for how much any individual should drink in a day (it varies based on age, activity level and other factors), she recommends using urine colour as an approximate guide: “If it’s pale, like the colour of straw, you’re drinking enough,” she says. “Anything closer to the colour of apple cider vinegar means you’re probably dehydrated.”
Get moving
Research has found that moderate-to-vigorous aerobic activity—in which the heart reaches at least 65 percent of its maximum rate—may help counter water retention associated with the menstrual cycle. Rizzo says these findings make sense; during exertion, your body heats up, which leads to water loss through perspiration (even if you’re not visibly sweating). Heavy breathing releases plenty of moisture, as well, Rizzo adds.
Consider magnesium
Although researchers have yet to conduct large studies on general populations, one study of 41 volunteers with persistent PMS found that those who took a 200 mg magnesium supplement every day reported less swelling and bloating after two monthly cycles compared with volunteers who took a placebo. Daily recommended intake for adults ranges from 310 mg to 420 mg. Speak with your doctor if you’re considering taking a supplement, or boost your magnesium intake through good dietary sources such as leafy greens, legumes, nuts, seeds and wholegrains.
Unpeel a banana
...or enjoy another food that’s rich in potassium. This is another nutrient that may help manage water weight by supporting the body’s elimination of excess sodium. The dietary guidelines recommend adults to consume 2,800 mg to 3,800 mg of potassium per day from sources such as spinach, broccoli, lentils, nuts, dried apricots and bananas.
The upshot: Should you worry about water weight?
Fluctuations in water weight are a normal part of being human. The body retains and loses water through energy storage, physical activity and other everyday functions. That said, it’s understandable if you find overnight weight gain unsettling—especially if you’re following a weight-loss plan. “If you gained 1.5kg, you [might] think that you can’t lose weight and may feel like a failure and throw in the towel,” Dr. Srivastava says.
Take heart and keep this in mind: “weight loss [is rarely] a perfect downward line; it will have natural fluctuations where it goes down some days and up other days thanks to water weight,” Harris-Pincus says, emphasising the value of long-term weight tracking and focusing on the overall downward trend, rather than the daily fluctuations
Water weight doesn’t carry the same health risks as weight gain associated with fat, experts say. In some cases, however, oedema (swelling caused by fluid retention) can be a symptom of a serious health condition such as a kidney disease. See your doctor if bloating, swelling or puffiness lasts for more than a week or is accompanied by other unusual symptoms, such as joint pain.
Many lifestyle measures that show promise for alleviating the discomfort of excess water weight—including getting regular physical activity, drinking plenty of water and limiting salt intake, are all part of an overall healthy lifestyle. Try them and you may find yourself feeling great in other ways, too.