Why They Happen, When to See A Doctor

EVER FELT THE desire to chuck your bathroom scale out the window?

Waiting for those three little digits to pop up may create a rollercoaster of emotions. One day you’re down the three pounds you’ve been looking to shed, the next you’re up three and back where you started. Regardless of if you’re trying to gain weight or lose weight, movement on the scale can get frustrating.

There’s good news, though.

Suzanne Manzi, M.D., obesity doctor of Performance Pain says weight fluctuations in men can be perfectly normal, especially if they are actively changing their diet and exercise habits. But, “if the fluctuations are significant and unexpected, then it may be cause for concern,” she says.

It’s normal for the weight on the scale to move up and down “few pounds over several days or even within the same day,” says Kim Yawitz, R.D., a gym owner in St. Louis, MO. That being said, if you’re losing and regaining the same 15 to 20 pounds over and over, that might be a cause for concern.

Sometimes, weight fluctuations may merit a trip to your primary care physician or another trusted health professional. If these weight fluctuations are big enough, they might indicate an underlying medical issue or unhealthy lifestyle, says Gabriela Rodríguez Ruiz, M.D., Ph.D., board-certified bariatric surgeon at VIDA Wellness. “In this case, it is important to speak to a doctor about your health and discuss the best way to manage any health risks associated with sudden or extreme weight fluctuations.”

Ahead, what experts want you to know about weight fluctuations.

What Causes Weight Fluctuation?

Like most health-related questions, there are many possible answers.

“Weight fluctuations can be caused by various factors, including changes in diet and exercise, hormonal imbalances, or underlying medical conditions,” Manzi says. Additionally, lifestyle factors such as stress, sleep patterns, and medications can all contribute to fluctuations in weight.

Short-term weight fluctuations are usually related to diet, exercise, and digestion. Something as simple as eating a high-carb meal can lead to fluid retention, which can cause temporary weight gain. This is because your body tacks on three-to-four grams of water for every gram of carbohydrate that’s stored in your liver and muscles, Yawitz says. You’ll eliminate that water weight by urinating as your body uses up those extra carbs.

“This is why rapid weight loss is so common on keto and other low-carb diets—because you shed water weight as you burn through your glycogen stores,” she says.

Other culprits of water weight gain? Both salty foods and intense weight-lifting workouts can increase fluid retention. Alcohol is a diuretic, so you may weigh slightly less the morning after a big night out, Yawitz adds.

The weight could also just be the big meal you had last night. On average, food takes about 55 hours to move completely through the digestive tract, so you might be up a few pounds if you’re constipated or have just eaten a lot of food.

How Much Can My Weight Fluctuate?

Again, there’s no single answer here.

“The amount of fluctuation in weight can vary from person to person, depending on their individual health and lifestyle,” says Rodríguez Ruiz. The safe range for weight fluctuation usually falls within one to six pounds. And, if it’s significantly more than this, it might be time to talk to your doctor.

That fluctuation range can happen even within a single day “thanks to variations in water weight and digestive contents,” says Yawitz. Don’t believe it? Try weighing yourself in the morning after going a little too hard at the all-you-can-eat.

It’s important to remember that temporary weight fluctuations aren’t particularly meaningful, she says. It doesn’t mean you’re gaining any significant fat or muscle.

“Most people care much more about fat and muscle mass, and changes to those require consistency and time,” she says. “It’s understandable to freak out if your weight suddenly increases three pounds overnight, but it’s also virtually impossible to gain that much fat or muscle in such a short time.”

Everyone is different, but an average-weight guy would need to be pretty consistent with his diet to lose even a pound or two in a week.

Should I Worry About Weight Fluctuation?

When in doubt, and you’re concerned about seeing shifting numbers on the scale, consult with a doc.

“If your weight is fluctuating significantly or rapidly over time, it is important to speak with your doctor about potential causes and health risks,” Rodríguez Ruiz says. “Your doctor can also help you develop a plan for managing any underlying issues or making lifestyle changes that can help you maintain a stable, healthy weight.”

Manzi suggests that it may be a good idea to keep track of your diet and exercise habits, as well as lifestyle factors such as stress and sleep patterns, to help you identify any potential triggers for weight fluctuations. Plus, saving a log of these factors may help your doctor formulate a plan to control your weight.

Is a Scale a Good Weight Tracker?

Your bathroom scale has its strengths, but also quite a few limitations.

“It’s great for monitoring long-term weight changes, but you shouldn’t put too much stock into any single weigh-in,” Yawitz says. If you want to keep track of your weight, step on the scale first thing every morning or at least a couple of times a week, after using the bathroom but before getting dressed.

As long as your average weight remains the same over time, or is trending in the direction you want, there’s no reason to worry. Curb the focus from on the number on the scale and more toward healthy habits, such as eating protein at every meal and walking at least 8,000 steps daily.

Bottom line: Losing or gaining a few pounds in a day or over the course of a week is likely not anything serious. If you come across any rapid, substantial, and unexplained weight change—such as gaining 15 pounds overnight— go see a doctor. If your weight fluctuations are big, but take time, “you might also want to speak with a registered dietitian if you struggle with yo-yo dieting, which can increase your risk of heart disease, high blood pressure, and stroke,” Yawitz says.

Perri is a New York City-born and -based writer; she holds a bachelor’s in psychology from Columbia University and is also a culinary school graduate of the plant-based Natural Gourmet Institute, which is now the Natural Gourmet Center at the Institute of Culinary Education. Her work has appeared in the New York Post, Men’s Journal, Rolling Stone, Oprah Daily, Insider.com, Architectural Digest, Southern Living, and more. She’s probably seen Dave Matthews Band in your hometown, and she’ll never turn down a bloody mary. Learn more at VeganWhenSober.com.