If you have a scale at home, you can weigh yourself anytime, but how often should you be weighing yourself anyway? Plus, what does that number really tell you about your health? Here’s what research and experts say about how often to check in on your weight—whether it’s to see how your weight loss journey is progressing or how your weight maintenance is going.
First, What Does Weight Even Tell You?
The number you see on the scale is the sum of your lean body mass—which includes muscle, organs, bones, and fluid like water and blood—and fat mass (also referred to as adipose tissue), Susan Kleiner, PhD, a dietician in Mercer Island, WA, and a national nutrition consultant, told Health.
“Your weight is simply a representation of the relationship of your body to gravity. On another planet, you'd weigh something else entirely. It tells you nothing about how healthy you are if you're pretty or any other moral assumptions we assign to the number,” said Kleiner.
Yes, weight is tied to your body mass index (BMI), a screening method for how your weight might relate to disease outcomes. BMI, which is your weight in kilograms divided by the square of your height in meters, tells you whether you fall into the underweight, normal weight, overweight, or obesity category. Typically, “the higher your BMI, the higher your risk for certain diseases such as heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems, and certain cancers,” according to the National Institutes for Health (NIH). But BMI has its drawbacks and may not be an accurate predictor of health for everybody.
Your weight—and BMI, for that matter—also doesn’t tell you the percentage of lean mass to fat mass (aka, your body fat percentage), which can be an important indicator of health. The more muscle you have, the higher your lean body mass, which equates to a lower body fat percentage. The more fat you have compared to your lean mass, the higher your body fat percentage. A 2016 study published in the Annals of Internal Medicine analyzed data on more than 50,000 adults aged 40 years or older and found that as body fat percentage increases, so does the risk for mortality.
Body fat analyzers, such as skinfold calipers, or methods like air displacement plethysmography (where your body fat percentage is measured while you're in a computerized, egg-shaped chamber) could tell you your body fat percentage, not a scale on its own.
But even though your weight alone won’t tell you your body fat percentage or overall health risk, research has shown that knowing your weight can help you engage in healthier behavior. For instance, a 2016 study in the Journal of the Academy of Nutrition and Dietetics found that weighing themselves daily led participants to engage in more weight control habits, like cutting down on sugary foods, eliminating excess snacking, and eating out less.
Read more How Often Should I Weigh Myself?
Should You Weigh Yourself Often?
If you’re embarking on a journey to improve your health, figure out whether weight loss should even be a part of that journey. “You can improve your health through nutrition and exercise without losing an ounce. If that’s the case, you don’t need to weigh yourself at all,” said Kleiner. “But if weight loss is something you desire, understand it’s a long-term process. You’ll see the scale go up and down, and only you can decide if weighing yourself will help or hurt your efforts.”
Here’s another thing to consider if you’re wanting to lose weight: “As your weight increases, you gain not only fat but also muscle mass to support the added fat. About 20% to 35% of excess weight is lean tissue, through the addition of muscle and bone mass,” Donald Hensrud, MD, associate professor of nutrition and preventative medicine at the Mayo Clinic College of Medicine, told Health. “You don’t need to lose the muscle you’ve gained, so weighing what you did in high school (or whatever arbitrary time point) isn’t realistic or helpful.”
Maybe your goal isn’t weight loss, maybe it’s weight maintenance. Either way, regular weighing might be beneficial. A 2014 review by Sage Journals examined the literature published between 1967 and 2013 regarding the use of daily self-weighing to control body weight and found weighing daily appears to be effective at preventing age-related weight gain. The study also found that frequent weighing correlates with losing weight and keeping it off.
However, it's not a one-size-fits-all decision. “For [one] person, checking your body weight daily might be a good thing. Or a different person can stay motivated by checking once a week. Yet someone else could find weigh-ins are self-destructive,” Kleiner cautioned.
A different review of the medical literature in 2015 in Current Obesity Records found that more frequent self-weighing was associated with poorer self-esteem as well as a negative impact on body evaluation, such as body image and body dissatisfaction. And though the results were mixed, the review also showed that studies have determined that some individuals will suffer from greater depression and anxiety if they weigh themselves often.
The review also revealed that self-weighing may be negatively associated with the development and exacerbation of disordered eating thoughts and behaviors. In fact, authors of a 2016 review in the International Journal of Eating Disorders wrote that, although weekly weighing is often part of the treatment for eating disorders, data suggest that even that frequency might prompt a moderately negative reaction. It’s best to consult your doctor or a mental health specialist if you have concerns or questions about the frequency at which you weigh yourself or its effect on you.
If you like the feedback weighing gives you, it doesn’t negatively affect your mood or mental health, and your health care provider hasn’t instructed you otherwise, weighing daily is likely best, Mike T. Nelson, PhD, a Minnesota-based exercise physiologist and national fitness and nutrition educator, told Health. “The problem with weighing less frequently is it puts a lot of pressure on one measurement. Some people will starve themselves the day before or do something screwy to try to make their weight lower,” Nelson said.
As for when you should weigh yourself, Nelson says to do it first thing in the morning after going to the bathroom. “Log it and go about your day. Then review the data once a week with an app that averages the highs and lows to show how your weight is trending over time, like Cronometer.”
What Causes Your Weight to Fluctuate?
If you are someone who weighs yourself on a more regular basis, you might notice that your weight goes up and down, even when you're not doing anything to purposefully lose or gain weight.
These are the most common reasons why weight spikes:
- Excess sodium. Nelson explained that salt causes your body to retain water, especially if you’re not used to eating a high amount. If you’ve ever felt puffy after a salty restaurant meal, you know how this feels.
- Carbohydrates. When we eat carbs, the energy we don’t use right away is stored as glycogen in our muscles. Each gram of glycogen carries three grams of water. This is why if you go on a low-carb diet, you’ll lose a lot of water weight in the first few weeks. The weight loss (or gain from a high-carb meal) isn’t fat, Nelson explained
- Fiber. Kleiner is a huge fan of getting your veggies, but she said to keep in mind that if you’ve recently upped your veggie consumption or switched to more plant-based or whole foods, you’re eating more fiber. You can experience temporary constipation, which makes your weight go up.
- Hormones. “Some females can swing five to eight pounds during their menstrual cycle,” said Kleiner. “For others, three to five pounds is common.” It’s not your period itself that causes weight gain. Rather, as the Office on Women’s Health explains it, the hormonal changes during that time might cause you to crave and eat more sweet or salty foods than usual, and those extra calories can lead to weight gain. It could also be from the retention of water weight during that time.
- Stomach contents. Many people forget that undigested food can cause weight to increase, according to Nelson. If you ate late in the evening or are weighing yourself at a different time of day, the amount of food in your gut can make a difference in your weight.
Nelson also explained that travel, alcohol, muscle soreness, poor sleep, and stress can also cause temporary spikes in weight. If you weigh yourself often, you can keep track of these factors and anticipate the weight changes they might bring.
There are also times your weight might drop overnight or during the week. Losses are most often caused by sickness that includes vomiting or diarrhea, or temporary dehydration. Nelson also explains that when some people are highly stressed, they can't eat, and their weight will drop until the stress abates.
Fluctuations in weight might also be due to underlying medical problems, something regular weighing might help you better pick up on. For example, out-of-the-blue weight gain can be caused by things like thyroid problems, heart failure, kidney disease, medication, and hormonal imbalance. Unexplained weight loss—defined by the Cleveland Clinic as either losing at least 10 pounds or losing more than 5% of your body weight over a period of six to 12 months—can also signal a host of medical problems, ranging from inflammatory bowel disease to cancer. Consult your doctor if you are gaining or losing weight and can’t explain why.
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What Are Other Ways to Track Your Health?
Again, the weight alone won't tell you much about your overall health. The following are other ways you can easily track your health at home that, together, can give you a more complete picture:
- Blood pressure: The National Institute on Aging defines normal blood pressure for most adults as a systolic pressure of less than 120 and a diastolic pressure of less than 80. Nelson advises getting an inexpensive blood pressure monitor to take readings yourself. High blood pressure is actually a metabolic risk factor that the National Heart, Lung, and Blood Institute says can raise your risk for heart disease and other health problems, such as diabetes and stroke, so monitoring is key.
- Waist circumference: This is another factor that the National Heart, Lung, and Blood Institute says can raise your risk for heart disease and other health problems. Excessive abdominal fat can increase your risk for obesity-related conditions, per the Centers for Disease Control and Prevention (CDC). Women are at higher risk if their waist circumference is more than 35 inches, men at 40 inches.
- Waist-to-hip ratio: The measurement can zero in on how much of your visceral fat (aka, the fat that’s stored deep in the belly, wrapped around the organs) is distributed in your midsection, per the British Medical Association. Central obesity can lead to mortality and disease risk, and the waist-to-hip ratio can shed light on that risk. To get this measurement, divide your waist circumference by your hip circumference. According to the NIH, for both men and women, a waist-to-hip ratio of 1.0 or higher is considered “at-risk” for undesirable health consequences.
- Sleep: Adults need seven or more hours per night, according to the CDC. Getting less than that on a regular basis has been linked with poor health, including a higher prevalence of diabetes, high blood pressure, heart disease, stroke, and depression. Nelson advised his clients to keep track of when they go to bed and when they wake up.
- Mental health: Taking care of your mental well-being is as important as your physical health. Trying a relaxing activity, staying connected, exercising regularly, eating healthful meals on a regular basis, staying hydrated, and practicing gratitude are all ways you can practice self-care, according to the National Institute of Mental Health. “I tell people, even if you don’t lose a pound, if you’re more active and you’re eating better, your health (physical and mental) is going to improve,” said Hensrud.