For anyone trying to lose weight or maintain weight loss, seeing the number on the scale increase even the tiniest bit can be disheartening. Especially when you’re working toward a goal, the last thing you want to see is an unexpected bump in the number after you’ve been diligently following a healthy diet and exercise plan.
But fluctuations in weight day-to-day are totally normal. “If you weighed yourself every hour throughout the day, you’d see dramatic shifts on the scale,” Amanda Foti, M.S., R.D., a senior dietitian at Selvera Weight Management Program, tells SELF. “I prepare every single one of my clients to experience these fluctuations at some point as they are guaranteed to see them regardless if they are eating and exercising perfectly.”
Even if you haven’t been 100 percent diligent—say, you spent a weekend at summer BBQs cheating up a storm—”it is not possible to gain 5 ‘actual’ pounds in one day or one weekend,” Dana Hunnes, Ph.D., M.P.H., R.D., senior dietitian at UCLA Medical Center and adjunct assistant professor at the Fielding School of Public Health, tells SELF. “It is possible, though, to retain 5 pounds of fluid in the body, particularly if you have been eating super clean.”
The reason you may feel like you magically gained weight overnight can vary. Here are the most likely causes:
1. You ate more sodium than you usually do.
Your body may retain excess water for a few reasons, but the most likely is related to your sodium intake. “If you consume more sodium than normal on a given day, your body will retain more water,” Foti says. Some people are more sensitive to this: For example, if you typically eat very fresh, whole, clean foods and work out regularly, and then forgo a workout and eat a super salty meal, chances are your weight fluctuation will seem more drastic than someone who typically eats more salt. “Mild dehydration can also cause your body to retain fluids,” Foti says. It sounds counterintuitive, but drinking more will help your body get rid of fluids more efficiently and flush excess sodium.
For most fluid-related weight gain, “assuming you go back to your normal eating and drinking habits, the weight gain should really only last 24 to 48 hours,” Hunnes says. “A lot of it will depend on how quickly your kidneys remove the excess water from your body, and whether or not you sweat out some of the excess fluid.”
2. Your plumbing’s a little backed up.
As you eat throughout the day, your weight may increase a few pounds until the next time you effectively empty out your bowels. If things are a little backed up, not only will you feel and look bloated, but your body will contain more weight than if you were to efficiently clear out the old to make room for the new. Make sure you’re eating enough fiber, staying hydrated, and keeping active so that your bowels can do their thing.
3. You’re weighing yourself at different times on different days.
“We can weigh 5, 6, 7 pounds more at night than we do first thing in the morning,” Hunnes says. Part of that is thanks to all the salt we consume throughout the day; the other part is that we may not have fully digested (and excreted) everything we ate and drank that day yet. “We weigh the least amount first thing in the morning after we have used the restroom,” says Hunnes. For the most accurate reading, weigh yourself naked right after you wake up and go to the bathroom. “This will give you a true sense of your true(est) weight.”
4. It’s almost that time of the month.
Hormonal changes right around your period can also increase fluid retention. Period-related weight gain will usually start five to seven days before your period and usually goes away by day three or four of the period, Hunnes says. “How big these fluctuations are really depend on the individual, but are usually between 2 and 8 pounds,” says Foti.
5. You’ve been carbo loading.
Eating a modest amount of healthy carbs is good for you, but eating too many so that you exceed your calorie needs (it’s easy to go overboard accidentally) can lead to both increased fat storage and extra water retention. “For every gram of carbohydrate you store as glycogen, your tissues must retain 3 grams of water with it,” Foti says.
6. You’re on the Pill or taking medication that causes fluid retention.
Some medications include potential side effects of weight gain. “In most, it’s due to a change in hormones causing an increased appetite and consuming more calories—aka true weight gain,” Foti says. “However, there are some medications, like steroids, that cause water retention resulting in what may seem like weight gain but is simply a fluctuation due to fluids in the body.” These fluctuations can be larger than those caused by diet-based water retention, and may not resolve until you go off the meds. “With this type of water retention you’ll likely feel the physical side effects in your extremities, puffy feet and hands,” Foti adds.