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How the Scale Lies to You

Scale saying weight loss

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“What gets measured gets improved.” – Peter Drucker

The scale can become something we dread stepping on. Seemingly random weight fluctuations on the scale can be very disheartening when we are trying to eat healthy, exercise, and lose weight.  However, I do believe that the scale is a tool that should be used daily on a weight loss journey. If not, we can find a way to play ignorant to weight gain. Doing so daily will help paint a better picture of how we are progressing rather than sporadic weigh-ins, as we will find out below. This helps us make course corrections on our weight loss journey. 

We will also learn how each individual measurement may not be an accurate gauge of our progress, which is why we need the multiple data points per week from a once-daily weigh-in. Let’s learn a couple things about our body to help keep the potential doom and gloom of a weigh-in at bay and turn the scale into a positive tool on our journey.

Trading Muscle for Fat

The scale does not always paint the whole picture of a body transformation. Especially for new lifters or those who have recently started lifting again, they may notice the scale does not move or stalls out for a few weeks while they are eating in a calorie deficit. 

This can be demoralizing, leading many to believe that they are not able to lose weight. However, as long as you are eating in a calorie deficit and fall into the category of a new lifter/starting lifting again after a break, the reason the scale may not be moving is because of the addition of new muscle. If you look at the picture below, you will notice that 5 pounds of fat has significantly more volume than 5 pounds of muscle.

The 5 pounds of fat will take up much more space under your skin than 5 pounds of muscle will.

What this means is that while you may be losing fat, the scale may not show this fat loss because you are increasing your muscle mass at the same time. One way to notice if this is happening for you is by simply looking at yourself in the mirror and seeing if you notice a change. Having a before picture can help you notice these changes. 

Using a tape measure to have starting measurements of key areas, such as thigh, chest, and waist, can also help as you can compare how the measurements are trending throughout the weeks. If you are losing fat, you should notice the measurements getting smaller, even if the scale does not move, because muscle is much more compact compared to the same weight of fat.

Weighing At Different Times of the Day

I personally have had weight fluctuations of 10+ pounds in a day when I compare a measurement in the morning to one in the evening. If you weigh yourself multiple times per day you will notice a similar trend. It is nearly impossible to gain any significant amount of fat (>1 pound) in a day so that means there is more at play. 

When we wake up in the morning, we have been fasting for several hours and have not consumed water for nearly as long. Our body has also been burning off energy while it makes repairs during sleep and has also been busy burning energy digesting our last meal. What this means is that we typically will weigh the least in the morning. 

Once we break our fast and start rehydrating our body, we start adding weight to our body again in the form of water and food. This typically means that the scale will record us as heavier and heavier the later in the day we chose to weigh ourselves.

For the most accurate tracking of progress, we want to be as consistent as possible with our measurements. Typically, this would mean weighing ourselves in the morning. This will give the most consistent results since we have not had the variability of different meals throughout the day. 

Different meals can cause our body to react in different ways. For instance, I can eat 32 grams of peanut butter (2 TBSP = ~180 calories) or I could eat 2 pounds of spinach (~200 calories). The calories are similar but the meal of spinach would make me heavier on the scale.

Extra Carbs and Salt or a Large Dinner

What we ate the day before can also play into what the scale shows. For instance, if we cut carbs, there will be rapid change in the scale. This is not necessarily fat loss, but is instead because cutting carbs from our diet means that the body retains less water. Therefore, if we cut carbs, we could notice a large weight loss, but it would not be just because of fat loss. 

Eating higher carb meals can lead to more water retention. Carbs are not bad. They just play a key role in water retention.

In a similar way, if we ate more salt than we typically do, we would also retain more water, leading to a heavier weight on the scale. This extra water retention from water or carbs is not a bad thing. For highly active people who sweat a lot, it is actually a very important thing. Do not be afraid of water retention, it is just something to be aware because it could affect the weight we see on the scale.

Furthermore, if we had a large meal the night before weighing ourselves, we could also see a higher reading on the scale because our body is still digesting this food and it has not moved through us to be used as energy or excreted as waste (AKA shit).


In the same way you can eat a meal that makes you retain more water, alcohol has the opposite effect. Alcohol causes your body to excrete more water, which is why you have to pee so much when you drink. Because of this, you are shedding water weight from your body. After a night of drinking, you may notice that you weigh less the next morning. This is because of the dehydrating effect of the alcohol. So while you may have packed on a lot of calories in the form of alcohol from the previous night, the scale would make it seem like you lost weight. Once you start rehydrating your body, the weight will usually come right back. Damn.

Fun fact: Drinking a lot of water before bed to try and beat a hangover is good, but not enough. You need electrolytes/salt to help the body retain this water. Try some electrolyte tabs or zero-sugar sports drinks.

Bonus Note: Bodyfat Percentage Scales

Certain scales have sensors that use bioelectrical impedance, as well as height, weight, age, and sex, to guess at your bodyfat percentage. This can be cool information to get from the ease of stepping on your scale but it is just a guess. These measurements can be as far off as 8% total body fat. This means that if the scale says you are 20% bodyfat, you could actually be as high as 28% or as low as 12%. That is the difference between having shredded abs or a prominent beer belly. 

This error range is in part because of how bioelectrical impedance works. The sensors you stand on send an electrical pulse through one foot, which travels up the leg, over the hip, and down the other leg. The scale takes a measurement of how long this pulse takes to travel from one sensor to the other and makes a prediction of body fat content based on this. 

The pulse travels fastest through water stored in the body, getting slowed down by fat. This means that your overall hydration level will play a part in what the measurement gives out. 

The scale also only measures through your legs, which ignores the upper half of your body. This can lead to inaccurate measurements based on where you are genetically predisposed to hold body fat. For instance, women tend to hold more body fat in their legs while men store more in their midsection. The scale uses equations to try and take the gender variables into account. However, everyone has genetic differences in where they store fat. This means that the scale will try to anticipate that women typically store more fat in their legs in its calculation. However, this specific woman might store a higher percent of their overall fat in their midsection than the average woman, which the scale cannot account for. What this means is the scale is guessing based off the limited amount of calibration test subjects the design engineer used. You are not going to have the same proportions that the engineer used as a baseline so your results will have inaccuracies. 

While the scale can only take an inaccurate guess at your body fat percentage, they do tend to be somewhat consistent. This means that while the number itself might be wrong, the scale will tend to keep showing a percentage that is about the same each time. As a result, you can sometimes use this tool to notice if your body fat percentage is trending up or down. There can also be some errors in this as well but it could provide some valuable insight into how you are progressing.

Image showing bodyweight over a few months
Graph showing my body weight over several months. This is during a phase when I tried increasing my calories to a slight surplus to increase my strength. It worked but I was not liking the extra fat I gained as a byproduct so I started a process of cutting while training to maintain as much strength as possible.
Graph showing bodyfat percentage over several months
Graph showing my body fat over several months. Notice that the data is consistent. While the actual percentage may be off by several percentage points, you can still notice a trend that follows my weight as I get heavier and leaner. Consistent but not always accurate. Still gives an idea of how you are trending.


A sudden weight gain in one day is nothing to be afraid of. It does not mean you put on extra fat. It usually just means you ate something that affected how your body retains water. It can take a few days for your body to adjust back to normal levels, depending on what you ate. Do not be demoralized. By looking at your average weight over the course of a week, you can gain a better understanding of how you are trending on your weight loss, maintenance, or gaining goals. There is no need to make drastic changes to your diet and exercise from one scale reading. You should wait until you notice it trending in the wrong direction over a couple weeks before making adjustments because just a few days worth of measurements is not enough to get the full picture.

Noticing these trends will help keep you aware so that you can make course corrections to keep you on track.

I use THIS cheap scale that comes with an app that neatly tracks and graphs your weight. The screenshots above are from the app. It is an easy way to watch progress.