You’ve probably heard that when you lose weight fast, it’s usually water weight. Or maybe you point fingers at water weight after stepping on the scale when you’re feeling totally bloated. But what exactly is water weight–and how do you get rid of it?

Water weight is when fluid collects in your tissues, causing them to swell–and it can make you feel pretty miserable. “Water weight is where the body retains fluid that normally would go to the kidneys,” explains Lynn Mack, MD, associate professor of internal medicine at the University of Nebraska Medical Center. Instead of peeing out that extra fluid, your body stores it between your organs and skin, she says.

That can be uncomfortable–but it’s usually temporary, and it doesn’t mean you’ve gained actual weight.

Of course, simply knowing that water weight often goes away on its own doesn’t make bloating or swelling feel any better. So here are some tips on how to both prevent water weight and lose it if it’s already there. 

RELATED: 5 Signs Your Bloating Could Be Something Serious

Causes of water weight

Salt and carbs. One of the most common causes of water weight is too much salt in your diet. Sodium binds with water and keeps it trapped in the body. “The higher the sodium in the diet, the more fluid retention a person will have,” says Dr. Mack.

Carbs can also have an impact on fluid retention, specifically if you start adding them back after a period of restricting them.

“The carbohydrates we don’t use right away for energy we store as glycogen,” explains Joanna Sheill DiCicco, a registered dietitian at Henry Ford Center for Health Promotion in Detroit. “Glycogen pulls in water, so the more glycogen we are storing, the more water we are taking in.”

“When we are on restrictive diets and at first lose weight quickly, that really is just water weight from the loss of stored glycogen from our muscles,” says DiCicco.

RELATED: 20 Little Ways to Drop the Pounds and Keep Them Off

Menstruation. Many women retain water weight the week before their period due to fluctuating hormones. Fluid retention may reach its peak the first day of your actual period, before subsiding for that cycle.

“With this type of fluid retention, the breasts can get really tender and some women get belly fullness,” says Dr. Mack.

You might also notice swelling in your face, legs, arms, and pubic area in the days leading up to your period.

RELATED: Here’s How PMS Can Change in Your 20s, 30s, and 40s

Pregnancy. Pregnancy can cause you to gain water weight, especially as you get closer to your due date. You may see swelling in your hands, feet, or ankles. Hormones are partly to blame, but your growing baby also puts strain on your blood vessels.

“With pregnancy, you have a big belly so the [pressure causes] the fluid to go out into the tissues, and it has trouble getting back into the vessels,” says Jennifer Wu, MD, an ob-gyn at Lenox Hill Hospital in New York City.

If your only symptom is swelling, it’s probably normal (although the weight may not all come off the minute you deliver your baby). If you have sudden swelling that hurts, you may have developed a blood clot (especially if the problem is only in one leg) or a spike in blood pressure. Either way, if you have these symptoms, get to a doctor right away.

RELATED: 17 Things No One Tells You About Recovering From Childbirth

Hormonal birth control. Just like there’s a connection between pregnancy and menstruation and water retention, hormonal birth control can also sometimes cause water weight.

Both the estrogen and progestin in birth control pills can be culprits, says Dr. Mack. Usually the water weight isn’t major and doesn’t last long, Dr. Wu adds, but you may want to talk to your ob-gyn about other birth control options.

RELATED: The Most Effective Birth Control, Ranked

Cortisol. Cortisol is best known as a “stress hormone,” although it’s actually much more than that. It’s involved in keeping blood sugar levels stable, balancing metabolism, reducing inflammation, and even forming memories.

Water retention as a result of elevated cortisol levels isn’t common, but it can happen.

“You’d have to have a pathophysiologic release of cortisol for that,” says Dr. Mack. In other words, there would have to be a lot of cortisol. “Just being stressed won’t do that.” (Phew.)

Cushing syndrome, for instance, might cause water retention. This is when tumors on the pituitary or adrenal glands release too much cortisol into the blood. People with low levels of thyroid hormone (hypothyroidism) can develop swelling around their eyes, says Dr. Mack.

Travel. Sitting for long periods of time on cross-country flights or lengthy road trips can cause water retention.

“Your muscles contract literally from sitting for too long,” says Dr. Mack, and your feet and legs may swell in response as the fluid pools there.

RELATED: 13 Reasons Your Feet Are Swollen

Medications. Certain meds can cause you to retain fluid. These include drugs for high blood pressure like calcium channel blockers, corticosteroids, and nonsteroidal anti-inflammatory drugs (NSAIDs). Some diabetes drugs, called thiazolidinediones, also do this.

Your doctor or pharmacist will be able to tell you if fluid retention is a side effect of any medications you’re taking and if there are alternatives that might not cause water weight.

Poor circulation. Our circulatory systems become weaker as we get older, or sometimes as the result of a more serious condition like heart failure (which is also more common as we age), says Elizabeth Kavaler, MD, a urologist with Lenox Hill Hospital.

The valves in the veins of our legs, which are supposed to keep blood flowing upward to the heart, collapse a little, so the blood pools in the lower extremities and causes fluid retention.

“It’s physics,” says Dr. Mack. “You just get more pressure pushing down on those legs.”

How to lose water weight (or at least control it)

Avoid super-salty foods. It’s not so much the saltshaker on your table you have to worry about, it’s processed foods. These contribute about 75% of our salt intake, according to the FDA, since many use salt as a preservative.

“All of your processed, packaged foods are going to have more sodium simply because [the manufacturers] want them to stay on the shelf longer,” says DiCicco.

Cook from scratch when you can, using non-processed items like fresh fruits and vegetables. If you do need a packaged item, read the label and compare sodium content across similar products.

RELATED: 25 Surprisingly Salty Processed Foods

Drink MORE water. You might think that putting more water into your body just adds more water weight. In fact, the opposite is true. If your body feels starved for water, it will hold on to whatever water it has.

If you’re retaining water, make sure you’re getting plenty of H2O, especially if you’re also eating salty foods.

It might also help to limit tea, coffee, and alcohol, all of which can be dehydrating. Cranberry juice, on the other hand, has a slight diuretic effect and may help flush out some excess water.

To get our top stories delivered to your inbox, sign up for the Healthy Living newsletter

Exercise regularly. Physical activity is key to losing water weight. Not only will you be sweating out some fluid, but you’ll also get thirsty and want to drink more water, says DiCicco.

Moving around can also help decrease puffiness. If you’re driving long distances, stop the car at regular intervals so you can get out and stretch your legs. Walk around when you can on planes, buses, or trains, and do simple exercises with your feet and legs while seated.

Regular exercise is also important if you’re pregnant (although resting with your feet up is smart as well).

RELATED: Tracy Anderson’s Favorite Exercises to Do While Traveling

Eat hydrating foods. This is almost as good as drinking water. “Foods that have a high water content help with increasing one’s overall hydration,” says DiCicco. Taking in more fluids–even in the form of hydrating foods–will ultimately help your body excrete water, she says.

Watermelon, spinach, strawberries, and cantaloupe, among other fruits and veggies, all have a lot of water.

Eating potassium-rich foods like tomatoes and sweet potatoes (and most fruits and vegetables) can also help you get rid of excess salt, says DiCicco.