Why Does my Bathroom Scale Fluctuate?

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Your past experience with scales may have been frustrating. You may weigh yourself in the morning and the scale will display a certain weight. When you go through the same actions the afternoon many scales tend to show a number higher than the first.

Don’t be too alarmed if this occurs. It’s normal for the scale to fluctuate even up to 10lb during the day. This doesn’t mean your scale is broken.It may simply mean your body’s weight is fluctuating. This is a normal occurrence. You may feel more at ease if you know why scales fluctuate.

Below we discuss various reasons.

Water Retention

You’re at your lightest when you wake up in the morning. When you consume your first meal for the day it tends to increase your body weight. It does this because your body is no longer void of food and this affects the water composition of your body.

Water retention causes your body’s weight to fluctuate. Almost anything you do affects the water retention which then affects the bodily composition.Let’s look at some reasons for this.

Sodium Intake

One of your body’s functions attempt to create a perfect balance between the salt and water that are in your system.

When you consume salt this tips the balance in favor of it. Your body reacts by retaining more water and this leads to readings that show weight gain.

When you eat less salt, your body will have the opposite effect and your readings will be lower.


Insulin in your body converts sugar into energy or fat. Over indulging in sugars leads to a high insulin level in your blood. The high insulin level makes you retain sodium which leads to water retention.


Alcohol is another element that affects the water retention in your body. Alcohol causes your body to dehydrate which results in water retention.

Your body tries to make up for the difference in your body’s water levels. This then affects your weight.

Carbohydrate Intake

The carbs that you consume result in a complicated process. This results in your weight fluctuating:

  • The body converts most carbs consumed into glucose for energy.
  • The energy is stored in the liver.
  • Glucose that your body didn’t use for energy gets converted to glycogen.
  • Glycogen is stored in the muscle tissue.
  • This then leads to water retention.

The water retention leads to scale readings that show weight gain. Therefore, some people switch to a low carb diet because it makes you lose weight quickly.

With low carb diets you aren’t necessarily losing fat. The body uses the stored glycogen for energy which causes less water to be retained.

Strength Training

When you work out your muscles you cause trauma to them. The muscles rebuild themselves after the trauma which make you stronger or more toned.

Once again water retention is a culprit in your weight fluctuating. When your muscles rebuild they need to retain water. Theyneed it because it speeds up the recovery process.

Menstrual Cycle

This reason obviously affects women. Prior to a menstrual cycle starting a woman’s estrogen level peaks. At these peak levels your body retains fluids.

This fluid retention makes you bloated and causes you to gain water weight.

Remember that if your weight is fluctuating during the day it doesn’t mean there’s a difference in your actual fat or muscle weight. Your scale can’t determine where the additional weight comes from. Use other methods such as photographs or measuring your body parts to also keep track of your weight losing process.

Additional Tips for Weighing Yourself

To get the best accurate readings it’s highly recommended that you follow a routine. This routine will give you a more consistent result:

  • Wear the same clothes or garments every time you weigh yourself. Your clothes can add more weight to the overall total. Weighing yourself with different clothing results in an inconsistent weight.
  • Weigh yourself the same time each day. As mentioned your body weight changes during the day. The best time would be to weigh yourself in the mornings before you eat. Your body is at its lightest and generally at its truest weight.
  • Pick one day of the week to weigh yourself and stick with it. It keeps tracking more consistent.
  • Scales are sensitive so make sure you stand in exactly the same position each time.

Is the scale broken?

If you don’t see a change in your weight then this could mean your scale is broken. Here’s how you can confirm it.

Zero Out the Scale

  • Analogue scale: Push down on the scale and release. The needle must fall on zero. If it doesn’t turn the dial to zero.
  • Digital scale: Perform the same procedure. To balance the scale, push the digital button.

Test the Scale

Test the scale with an item that you know the weight of. You can place an unopened bag of sugar of flour on the scale. The weight of these items must be heavy enough for the scale to register it. Check your manual for minimum measurements the scale is capable of.

For a guaranteed weight measurement, you can also use a hand weight used for exercising.

Weigh the Item Multiple Times

Weigh the item a couple of times and write down the reading each time. Make sure the scale resets to zero before weighing the item again. If the true weight of the item is displayed then the scale isn’t broken.

Weigh Yourself with The Weight

If you weigh approximately 120 lbs and you hold a weight of 5 lbs the scale must read 125 lbs. If the number is significantly higher or lower than what it should be then the scale is broken.

More Reasons for Inaccuracies

If you see your scale gives highly inaccurate readings not related to your body’s hydration you may be faced with one of these problems:

  • The scale isn’t level
  • The scale isn’t on a firm enough surface
  • The sensors are damaged
  • Software is malfunctioning
  • Other devices such as microwaves cause wrong readings
  • Rough handling damaged your scale

You can see fluctuating readings can be due to human or mechanical faults.


You don’t have to suspect problems the first time you see fluctuating readings. It may simply be your current diet. You can however keep an eye on readings for a few days. Technology does wonders for our fitness routines but it’s also very sensitive. Test your scale from time to time so you know you can still trust its output.

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