Weight fluctuations mean that body weight increases and decreases over a given time.

We’ve all experienced the Monday morning scale scaries. After a weekend of cocktails and burgers, you ever-so-timidly step on the scale to check the difference — only to do a double-take.

“Wait, I gained how much weight?”

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Before you seriously lose your chill or sign your life away to a punishing diet regime, take heart. It’s actually totally normal for your weight to fluctuate in within a 5-pound range.

Here’s what to know about the how, the why, and the how-much behind wavering weight levels.

“Everyone’s weight fluctuates throughout the day, and especially from morning to night,” says dietitian Anne Danahy, MS, RDN. “The average change is 2 to 5 pounds, and it’s due to fluid shifts throughout the day.”

As no two people are built the same, there’s also no real definition of what a “normal” weight fluctuation looks like, according to a 2019 review.Zou H, et al. (2019). Body-weight fluctuation was associated with increased risk for cardiovascular disease, all-cause and cardiovascular mortality: A systematic review and meta-analysis. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856014/

If you see fluctuations of less than 5 pounds, you needn’t worry. However, a higher level of variation could imply you have a health issue that needs addressing. Those who live with disordered eating often experience major weight fluctuations in a short time period, for example.

Alternatively, says Danahy, “If someone’s kidneys aren’t working properly, it may signal that they’re holding on to too much water. Fluid retention can also be a sign of other health conditions like congestive heart failure or lung disease.”

If your weight yo-yos over 10 pounds in either direction, it’s best to get it checked out by the pro-pros.

Okay, so, under regular circumstances, is there anything you can do to keep the number on your scale from swinging like an unhinged seesaw on Mardi Gras? Possibly.

You can always try scaling back on salty foods to keep excess fluid at bay. “It’s certainly smart to eat less sodium by cutting out processed foods,” Danahy advises.

But slashing your calories to avoid a minor rise in weight isn’t the way to go.

“Restricting calories too much won’t help, and in some cases, it might make matters worse. Protein levels in your body help regulate your fluid balance, and if you’re deficient, you’ll retain more fluid.”

Nobody wants that. Make sure you keep yourself stocked up on high-protein snacks, dinners, and breakfasts — even desserts can be a good protein source.

A daily swing of 5 pounds can seem like a lot (especially if you’re a smaller person). However, in the grand scheme of things, it’s actually a pretty low number, considering all the factors that can alter body weight.

Eating a large meal

First, there’s the obvious: If you ate a large meal yesterday or are weighing yourself at the end of a weekend of excesses, it’s only natural to see an uptick.

But this may not mean extra weight has already made its way to your thighs or tummy.

Instead, it could be food that’s, um, on its way out. According to 2015 research, a healthy adult unloads an average of 128 grams (about a quarter pound) per day through poop.

Types of nutrients

Meanwhile, the types of macronutrients you took in through last night’s beer- and burger-fest can change the amount of fluid your body hangs on to.

“When nutrients like protein and carbs are stored in your body, they store water along with them,” says Danahy. In fact, for every 1 gram of carbs your body stores as glycogen, it retains 3 grams of water.Fernández-Elías VE, et al. (2015). Relationship between muscle water and glycogen recovery after prolonged exercise in the heat in humans. https://pubmed.ncbi.nlm.nih.gov/25911631/

Sodium, or “salt” to its friends, is another common culprit in the back-and-forth dance you may see on the scale.

This mineral pulls water into the bloodstream — which can not only raise your blood pressure but also create a bit of extra heft in the weight department.

Being on your period

Finally, for people with female reproductive systems, being on your period can come with significant water weight.

The drop in progesterone and estrogen that cues Aunt Flo’s arrival also triggers fluid retention. One study found that 65 percent of women experienced swelling related to PMS.Tacani PM, et al. (2015). Characterization of symptoms and edema distribution in premenstrual syndrome. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4362892/

The day of the week

After a weekend of booze and takeout, your weight is naturally going to sit a little higher than after your more restrained weekdays.

This isn’t just common sense — research backs up that weight often starts to increase on a Saturday and decrease on a Tuesday.Orsama AL, et al. (2014). Weight rhythms: Weight increases during weekends and decreases during weekdays. https://www.karger.com/article/fulltext/356147 Take that, weekend!

The study reiterates that weight fluctuation across the course of a week is completely natural and shouldn’t be taken as a concrete sign of weight gain or loss.

Quick review: If your weight seems to be on a constant rollercoaster of mini peaks and valleys, it’s completely normal (within about a 5-pound range).

Food and fluid intake, sodium balance, bowel movements, and your menstrual cycle keep things in constant flux.

Considering all these day-to-day factors, it would be strange if your body didn’t have its ups and downs. “Weight fluctuations are normal and necessary,” notes Danahy.

In most cases, we probably just have to learn to live with a bit of variation at our weigh-ins.

Consistently losing 5 percent of your body weight throughout 6 to 12 months might point to a more severe health problem.

A jump or drop of 10 pounds or more isn’t likely to be the result of overdoing it on your favorite cheesecake or cranking out an extra-tough kickboxing class.

To accurately tell whether you’re losing or gaining weight, avoid stepping on those scales every day. (Doing so may cause an unhealthy fixation, as well as not really giving you an accurate reading.)

Instead, try a weekly weight check, or go by other measures, such as how well your jeans fit.

When you don’t nitpick every little ounce, you’ll probably stress less — and get a better sense of the true direction in which your weight is moving.