Two Scales Each Provide Different Weights. What is Going On?


Why do my scales say 2 different weights?

It's best to find one bathroom scale and stick with it for consistency.

But remember, your body weight may differ with time of day, even with an accurate scale you use consistently. For example, if you weigh in first thing every morning, your exact weight may be lower than if you weigh in at night after dinner. 

lady in sports gear checking her weight on her app

It doesn't mean you're getting inaccurate readings; it's just normal fluctuations in your body weight throughout the day.

That's why it's important to control for this variation by weighing yourself at consistent times and wearing similar clothing.

Here are some other things that can effect your scale's accuracy:

  • Calibration: Past shocking or jarring a scale such as dropping or kicking it
  • Age: Older scales can be less accurate. 
  • Humidity: Humidity can corrode a scale. (Humidity can also increase your weight.)
  • Manufacturer: Cheaper scales may have lower-quality components. 

Three Things to Know About Digital Bathroom Scales

1. Hard Surfaces Provides More Accurate Readings

 It's important to place your bathroom scales on a hard surface, like tile or wooden floors. That's because your weight needs to center directly on the scale itself. If placed on a softer surface like a towel or carpeted floor, your body weight will be distributed over the individual fibers in the material instead of concentrated on the scale itself. This can produce a less accurate reading.

2. Level Surfaces Provide More Accurate Measurements

 It's ideal to set up a bathroom scale on a level, flat surface. If a surface is irregular, then the scale may be off-balance. Your body weight may not be centered on the scale, usually where the weighing mechanism is. This can produce fluctuations if your weight is offset, leading to a slightly less accurate reading. 

3. Wet Skin Can Interfere With A Smart Scale

One advantage over analog scales is that digital scales often include bioimpedance analysis, or BIA for short. This means that the scale sends a weak electric current (don't worry, it's not gonna zap you) through your body. 

It can use your body's tissue resistance to compute the ratio of different types of tissue in your body. This includes fat content, bone density, muscle mass, and water weight. Wet skin conducts electricity well, so it should not drastically change your BMI or body mass reading if you weigh in after a shower.

 

Why am I different weights on different scales

Whether a new scale or an older analog one, different scales are likely to differ slightly in what they report. The analog beam-balance one at your doctor's office may give a different reading from your own scale. That's because each brand of scale may have different calibrations, and some scales may be synchronized for your own body type or BMI. If they're good scales, they'll probably get an accurate reading that's very close to your correct body weight. 

Should you use 2 scales to weigh yourself

Like we said before, each scale may be calibrated differently or differ in its mechanism of weighing you. Even two properly calibrated scales may report slightly different readings, but if they're quality scales, they should both be close to your correct weight. Therefore, it's better to be consistent with the scale you use and stick to the one you trust.

Can my bathroom scale be wrong?

From visits to the doctor's office and their appearance in the mirror, most people will have a general idea of their body weight. But if you step on the scale and it reports a very drastic weight loss or gain that doesn't feel right, it's possible your bathroom scale could be wrong. 

Most modern scales are of good quality, but defects do occur. Or sometimes, your scale may need to be calibrated. Be sure to check your weight units are correct. For example, a scale measuring in kilos may report a 150-pound bodyweight as 68 in kilograms, a vast disparity! 

Do scales remember your weight?

Analog scales typically don't remember your weight. But many new digital scales with BIA and corresponding apps do. Sometimes the scale itself will remember your weight and BMI, but they will often store the app's weight. The FitTrack operates this way: it stores the data from your scale in an app on your phone. That way, you can compare your weight and BMI over time to track weight loss or muscle mass gains. 

Note:The FitTrack stores your weight in an app but does not remember it on the scale. It tracks your trends day-to-day and also calculates an average weight to account for normal flucuations. 

Why does my weight fluctuate 10 lbs in a day?

Your body's mass is always changing. Even when you're sleeping, your body is still working. Your heart is still beating, your brain is still active, and your muscles are still working to help you breathe and digest. Your body is even more active during the day, using up more calories for energy. So just by existing, your metabolism is burning some of your stored fat and glucose. This causes some weight loss. 

But to stay alive, your must eat and drink. By putting mass into your body as food and liquids, you're increasing your body weight. You can easily clock in a pound or two higher after eating a large meal with several courses or heavy food like beef or carbohydrates. 

And even though water doesn't have any calories, it's still mass: try picking up a liter or quart of water; it can be pretty heavy! And salty or sugary foods may make you crave fluids, causing you to increase your weight by adding water when you drink it. 

Your body also excretes excess fluid and metabolites when you go to the bathroom. The average human bladder can hold from 200mL to one liter of urine. So when you urinate, you can drop almost a kilogram! You also lose water through sweating and breathing (even more so when your exercise), so your water weight is constantly in flux. 

The point is, it's normal for your body weight to fluctuate throughout the day, especially if you eat a big meal, drink a lot, or do strenuous exercise. If you compare your weight after waking up to before bed, you'll probably be a little heavier from eating or drinking throughout the day. It's also common for weight to increase on the weekends and decrease during the weekdays. Bear in mind a 10-pound weight change in one day is pretty severe and unlikely unless you are frequently going to the bathroom or are unable to go. 

How much weight do you lose overnight on average

During sleep, your brain and heart still work and burn energy, albeit at a slower rate than when you are awake. Your body also releases growth hormone during sleep, which causes your body to grow and repair your muscles and joints, also consuming energy. 

The average person burns about 45 calories per hour of sleep, so that you can burn up to a couple of hundred calories with 8 hours of sleep. Bear in mind that one pound is equivalent to 3500 calories, so it would take many, many hours to lose any noticeable weight just by sleeping. As mentioned before, simply going to the bathroom can shed more weight, so don't expect significant weight loss or other fluctuations in weight when you wake up. 

Why does my scale say I weigh less when I weigh myself on the carpet than when I weigh myself on a hardwood floor?

Carpet is made of several individual fibers, almost like a lawn of grass. When you step on them, the fibers yield and bend, distributing your weight over them and cushioning your step. This makes them very supportive and soft to walk on, but it doesn't create a level, flat surface. 

Hardwood, tile, concrete, or linoleum flooring is much firmer; these harder materials don't yield.  (That's why they feel harder too). When you step on them, your weight is centered directly on them. That's why your weight is more likely to be accurate if you set the scale on a hard, flat surface. 

Think of when you're carrying a backpack or messenger bag: if you're holding it in one hand, all the weight is focused on your arm. But if you sling it over your shoulder or back, the weight is dispersed over your body and appears lighter. Placing your scale on the soft carpet will do something similar, by spreading your weight over materials in the individual fibers. Your weight hasn't changed, but spreading it over more surface area can lessen its effect on the scale. 

References: 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3494104/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5644907/

https://pubmed.ncbi.nlm.nih.gov/8627466/

https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=41&ContentID=CalorieBurnCalc&CalorieBurnCalc_Parameters=160

https://eatsmartproducts.com/knowledge-base/three-things-to-know-before-using-a-digital-bathroom-scale/