Why is my weight yo-yo’ing all the time?

I never weigh myself unless I’m at the doctor’s office—the numbers don’t mean much to me unless my clothes cease to fit—but those of you who are more diligent (because, for you, stepping on a scale is a healthy part of how you check in with your bod) or routinely curious may notice nearly incessant fluctuations in the figures that appear on the screen.

This can be either maddening or a pleasant surprise—”I ate only pizza yesterday and lost 3 pounds, I guess I should always eat only pizza!” But, what *actually* makes the numbers dance? (Spoiler alert: It’s probably not your pie-centric interlude.) Below, find a thorough exploration of weight fluctuation, including when and how to rein in your body’s yo-yo’ing tendencies.

Keep reading to find out why your scale can’t seem to make up its mind.

You ate or drank something

No, consuming a cookie (or even an entire sleeve of cookies, occasionally) isn’t going to make you gain permanent weight—so stop guilt-tripping yourself! However, you may see scale numbers rise temporarily. Dana James, a board-certified nutritionist, functional medicine practitioner, and cognitive behavioral therapist, says that normal weight fluctuations throughout the day can be caused what you eat and drink as well as whether you’ve expelled waste. (Fiber it up, girls!) “I once had a male client who came to me at 2 p.m. without eating or drinking anything all day to get a lower number on the scale. I took the number then had him get on the scale again after drinking a glass of water. The number immediately went up,” she tells me. Dana Hunnes PhD, RD, a senior dietician at UCLA Medical Center, tells me that such daily weight gain can reach numbers as high as eight pounds.

You’re retaining water

If you’re retaining water, sodium could be the culprit. Dr. Hunnes describes it as a “water-loving molecule” and says that the more salt we eat, the more likely we are to store H20; however, it’s important to note that the bulk of your sodium intake likely comes from processed foods rather than the Himalayan sea salt dashes you’re adding to your home-cooked meals. Also, Dr. Hunnes tells me hormones may affect the amount of sodium excreted by the body, which means there may be fluctuations in water retention throughout your cycle as a result.

Carbs, she says, can also increase water weight, though they’re unlikely to do so if your diet is consistent (e.g. you don’t eat only pizza after weeks of being carb-free). To this, James adds a caveat, however. She says she’s seen patients with gluten sensitivities gain between three to eight pounds after consuming gluten, something which doesn’t happen to her non-sensitive patients. (Not sure if you’ve got a gluten sitch? This is how to find out.)

Progesterone levels may contribute to water weight as well. In the later stages of your menstrual cycle, James says, levels of this hormone rise, which may contribute to a bloated feeling and higher numbers on the scale. “It’s typically two to three pounds,” she explains. Try seed cycling to balance your hormones and potentially reduce this symptom.

Finally—as anyone who’s ever been on a plane knows—James says air travel may be to blame for your water weight; here, find 13 ways to beat this bloat.

You went H.A.M. on vacation

Filed under things you don’t want to hear: In some cases, the scales don’t lie. If you binge on vacation, you may *actually* gain real weight; however, it’s not as easy to do as you may think. “Since it takes approximately 3500 excess calories to gain one pound of ‘true’ weight (as opposed to water weight), it would likely take an average person anywhere between five to seven days to gain weight,” says Dr. Hunnes. “If you binge for a week of vacation, you will likely see the scale move several pounds, but most of that will be water weight.”

So, about three to five days after returning to a normal routine, Dr. Hunnes explains, you should be able to identify how many pounds you’ve actually put on—likely no more than a couple. If you then aim to lose these extra lbs, Dr. Hunnes advises cutting 200 to 300 calories a day from your diet and/or exercising more intensely. “Cutting alcohol will definitely help,” she adds in news that’s likely to make your post-vacation blues extra bummer-y.

Your weight doesn’t tell you much about your health—here’s how to actually find out if you’re well. Plus, discover  why you should probably diet to shed inflammation rather than pounds.