Body Composition: The Scale Says You’re Fatter? Not Necessarily.

body composition

Maria here with a body composition story that luckily had a happy ending:

I was excited to do the final wedding dress fitting one week before my wedding. Still jet lagged from my trip from the US to Europe, I took the dress in my hands, walked into the tailor’s dressing room and tried it on.

I rushed to get out to look myself in the mirror. The tailor was right behind me expecting to claim “victory.”

Instead this happened:

“You lost weight!” said the tailor. “You didn’t tell me you planned to lose weight!”

“But I didn’t lose any weight! And I wasn’t planning on losing either!” I answered back in my defense.

And that was true. I weighed exactly 57 kg back in November when we did the first fitting and I tried the dress on for the first time. And I was exactly 57 kg this first week of July, when I put the same dress on, only this time it had too much fabric for my needs – too big around the chest, too big around the waist, the tailor would have to rush to make adjustments as the wedding was due in a few days!

So what had happened? Why even though I weighed the same did it look like my body had shrunk?

Changes in body composition, that’s what had happened. You see after the November appointment when the dress was ordered and the fitting was done, I started exercising more. I had gone from 2 times a week to 5 times a week consistently, week after week.

I hadn’t realized just how much my body had changed in those 7 months until my final wedding dress appointment, which is why I was as surprised as the tailor to see that the dress was no longer fitting as it should.

I explained to the tailor that I hadn’t been on a diet; it was exercise that caused these changes as muscle is denser than fat and I had apparently put on muscle while I’d shed fat; But the annoyed tailor wouldn’t believe the body composition facts I laid on him and kept on rumbling about my “weight loss” and why did I not let him know in advance I was planning to “diet?”

(I swear I had not dieted at all!)

The story has a good ending – the tailor may have dismissed my body composition facts but he did make the changes on time. The dress fit exactly right on my wedding day:

body composition

And I got a first-hand experience on what changes in body composition really mean and how our weight is not an accurate measure of our fitness and should never be relied upon exclusively.

So if you’re looking to lose weight, what you’re really saying is you’re looking to lose fat. Those two should NOT be confused. You’re using the number on the scale as a proxy for fat. But don’t forget it’s just a proxy.

Enter Tommy who’ll explain all you need to know about body composition and how to measure whether you’re really losing fat – regardless of whether your weight is going up or down.

Body composition is why I now have an overweight BMI, while I don’t look like I’m overweight.

This is me Tommy; The picture the left shows me before I was a lifting, and the one on the right after I got into lifting.

Body composition

Despite my now overweight BMI, I don’t look like I’m overweight right? That’s what body composition does to you.

What is body composition?

In short, body composition is the ingredients your body is made up of. Like you categorise foods into their food groups, the different components of your body can be separated into different compartments.

The specific compartments your body is broken down in to depends on the way they’re being measured/estimated, but for simplicities sake, we will stick to the two compartment model that splits your body into [1] fat mass, and [2] fat free mass.

What does body composition consist of?

1. Fat mass refers to all body fat, not just the fat around your belly.

Unsurprisingly, fat mass is all the fat contained within your body. It’s not just the puffy stuff that covers your hips, tum, and legs though; it encompasses all body fat, including that found in organs, bone, and muscle (1,2).

Typically, women have higher levels of body fat than men, primarily due to differences in hormonal profiles (3). The spread of body fat also differs between sexes, with women having proportionally more fat on their hips, bum, and thighs (known as a gynoid pattern), whereas men’s fat tends to be skewed more towards their upper body and trunk (android pattern) (3).

2. Fat free mass is everything else: muscle, bone, fluids, etc.

Everything else that isn’t fat is bundled together under the fat free mass compartment. In other words, muscle, bone, vital organs, and extracellular fluid. Again, there are sex differences here with males typically having greater levels of fat free mass due to larger muscles, bones, and organs (1). There are also ethnic differences with black individuals typically having the highest FFM numbers (4).

As I said, the body can be broken down into more compartments that the two above, with some methods separating bone from the other components of fat free mass for example (eg: dual-energy x-ray absorptiometry/DEXA). To be frank, you don’t really need to know all the ins and outs of the different compartments though, and the main thing to take home here is:

Your body is made up of multiple components that include fat, muscle, bone, fluid, and much more.

Now, the reason why it’s so important to understand that the body is broken up into these different components is they all contribute to your total bodyweight.

And because the different components vary in their density, and can contribute to your weight to varying degrees over the course of the day, week, and month, your body weight at any given time may not actually be a reflection of your physique.

So your weight can and does go up and down even if your body fat doesn’t change an ounce, meaning you shouldn’t get too hung up on the number you see on the scale.

Allow me to explain:

Body Composition: 3 reasons why tracking your weight is not the same thing as tracking your body fat.

Weight is often a proxy metric we use for fat. However, losing weight does not necessarily mean losing fat just like gaining weight does not necessarily mean you’re getting fatter. Here’s why:

1. Your weight naturally fluctuates day to day, even though your body fat might be stable.

Body composition

Amongst many other factors, the amount you sweat, eat, and drink can cause your hydration levels and bodies stores of carbohydrates (glycogen) to change pretty dramatically over the course of the day.

This can have a knock on effect on your weight.

For example, let’s say you finally rock up to that exercise class you’ve been promising yourself you would start getting involved in months ago.

After an hour of knee raising, pad punching, and, unfortunately for you, burpee jumping, you’ve worked up quite the sweat. In fact, your shirt is drenched in the stuff, amounting to a total of 1 litre of fluid lost as sweat; a standard amount after an hour of hard exercise (5).

You also burnt through a hefty sum of stored energy by firing all your muscles and cardiovascular system during the exercise. Because the exercise was of a high intensity, a lot of the fuel used by your muscles was your bodies stored carbs (6). This amounted to a total of 60g of stored carbs used over the hour. In your body, carbs are stored bound to water too, and for every gram of carbs you use up, you also lose 3 grams of water, further adding to your acute weight loss.

So, from your hour of exercise alone, you’ve dropped a total of around 2.75 pounds: 2.20 pounds of sweat and 0.55 pounds of glycogen (stored carbs).

Because you forgot to weigh yourself pre exercise like you usually do, you jump on to the scale when you arrive back home and are pretty chuffed that you’re down a couple of pounds from last week. You give yourself a pat on the back, down a protein shake in celebration, and have a revived sense of motivation to keep nailing your diet. Good job.

After a week of faultless dieting, you’re prepping for your exercise class again, but this time you remind yourself to pop on the scales PRE-workout.

You’re confident that your solid week of dieting will sit you down another pound or two compared to last week, and are optimistic as you take the step onto the bathroom scales.

To your horror, the number you envisioned in your head doesn’t match up with the one showing up on the scale. You’re not down a pound, nor are you the same weight as the previous week; you’re actually a whole 2 pounds heavier, putting you back to where you were two weeks ago.

Because you’re yet to discover Fitness Reloaded and this article, you step off the scale disheartened by the apparent backwards step you’ve taken on your weight loss journey.

The thing is, the two weight recording are not comparable as they were taken under completely different conditions: one post sweat ladened workout, and the other pre. This inconsistency meant that some highly variable components of your body composition (eg: extracellular fluid, carbohydrate stores) fluctuated, throwing off your weight recording so it wasn’t a true representation of the progress you made.

You also can’t draw conclusions on your progress based on recordings taken this close together either, as many other components of your body composition can fluctuate over the course of the day and week; not just body fat.

To demonstrate this, below is a graph of my weight over the course of a few months dieting. I’ve highlighted a couple of individual recordings in red to show just how dramatically bodyweight can fluctuate on a day to day basis.

Body Composition

In this example, my weight differed by up to 2kg day-to-day, which could have only been due to changes in body composition components such as extracellular fluid, and also factors like the amount of food in my digestive tract.

And on that note, here’s a list of just some of the factors that can influence your weight:

  • Body fat
  • Hydration
  • Body carb stores
  • Poop and wee
  • Organs
  • The surface your scales are sat on
  • Food in your digestive system
  • Clothes you’re wearing
  • The scale itself

Many of these can and do fluctuate a great deal in the short term, meaning you should take a more long-term outlook on your weight loss progress.

2. Got ovaries? Your menstrual cycle affects your weight – again nothing to do with your body fat.

Body composition

In comparison to your daily weight fluctuations, longer term changes – as in those seen over the course of a month – are more likely to be reflective of your changes in body fat.

But again, it’s not all that simple, particularly for women. You see, the hormonal changes that occur over the course of the month cause variations in water retention. This means that your body may hold on to extra water on some weeks more than others, which impacts the number that you see on the scale.

Lyle McDonald, a highly respected nutrition and training expert, breaks it down nicely here:

Body Composition

So the fluid component of your body composition can fluctuate a great deal both in the short and moderate term. This means that you should take weekly fluctuations in weight with a pinch of salt, particularly if you’re a woman.

Instead, you should look at longer-term changes before you can draw conclusions as to your weight loss progress.

By that I mean you should look at the trend in your weight over the course of months, not a few days or weeks. Only then can you start to get a reliable picture of your weight loss progress, which may be indicative of changes in body fat.

Even then, the number you see on the scales can be somewhat misleading though.


Because the different components of your body (ie: body composition) are different densities (8).

3. Exercising? Your weight may be stable while you’re losing inches all over.

Body composition

You know when people say muscle weighs more than fat?

Well, if you take a second to think about the statement, it becomes pretty clear that they’re wrong as a pound of fat will weigh the same as a pound of muscle; just like a pound of feathers weights the same as a pound of bricks, iron, or peanut butter.

What they really mean is that muscle is denser than body fat, which is very much true.

In other words, a pound of muscle is smaller and takes up less space than a pound of body fat.

This difference in densities means that you can trim down on the fat and consequently tone up, but if it coincides with a gain in muscle (which often is the case if you start lifting weights for the first time), you may not see a change in scale weight.

Ultimately this means that you may start to tone up, and develop that J.Lo-esk physique you’ve been after for years, yet the weight doesn’t seem to budge.

Heck, you could even GAIN weight, yet be far happier with the body you see in the mirror.

In fact, that’s exactly what has happened to me over my years of throwing weights around in the gym.

The left is me a few years ago when I admittedly had some outrageous hair going on and was classed as a healthy weight by conventional standards. The right is me now after a few years of lifting:

Body composition

(Yes, this is the same picture with the one I shared before. Because I’m vain like that.)

Now, I pride myself in being in somewhat decent shape, having committed to training hard consistently for a number of years.

The thing is, technically I’m actually overweight now. At least that’s what my BMI says, given that I weigh in at 86kg, whilst standing 6’1 tall (more on this another time).

Although, unlike me, most women won’t have any desire for boulder shoulders, bulging biceps, and chiseled abs, many will rightly take up weight training to help them achieve their dream physique as it helps creates that toned look.

And with this resistance training, often comes the pattern I’ve described above: changes in the mirror but not so much on the scale.

So, to prevent you getting disheartened by the scales, you should:

  1. keep in mind what I’ve outlined above and understand when to take your bodyweight with a pinch of salt.
  2. monitor your progress effectively with the following methods.

So if tracking weight is inaccurate, then how can you really know whether you’re losing fat or not?

1. Weigh yourself the RIGHT way.

Whilst it might seem as though I’ve slated the scale somewhat by what I’ve said above, weighing yourself isn’t pointless at all. In fact, it’s the most common method I use to assess my clients’ progress. You need to know how to do it properly though, which is done by controlling the variables that can end up screwing it up.

In a nutshell, you need to keep the conditions you record your weight in as consistent as possible. That means:

  • Wearing exactly the same clothes each time. For this reason, I suggest you weigh yourself in your undies only, or in your birthday suit.
  • Weighing yourself at the same time each day. Ideally it should be done soon after waking up, pre food/drink, and post toilet trip.
  • Using the same scale sat on the same surface. Different scales may give slightly different readings and you’ll screw up your consistency if one day you place it on your bathroom floor, and the next it’s on the carpet. In an ideal world, you should weigh yourself when the scale is sat on a solid surface

Because your weight can fluctuate so much, it’s also best to take a number of recordings over the course of the week and then work out your weekly average. I generally suggest 3 or more recordings per week as this will give a better picture of the changes in your weight over time.

2. Get your tape measure out.

In combo with weight recordings, taking monthly circumference measurements are a great tool for assessing changes in your physique.

From a weight loss perspective, the main site to measure is waist circumference. Simply wrap the tape measure around the smallest part of your waist and record the number. Again, the most important thing here is consistency so make sure you measure the same place each time.

The Jeans Test is also a great little tool to use that will tell you whether your waist circumferences is getting fatter or thinner, and whether you’re trimming up the tum. Maria shows how she used the Jeans Test on the Flat Belly Firm Butt program in the clip below:

3. Take progress pictures.

Regardless of the scale weight or tape measure reading, it’s the physique in the mirror that most of us want to transform. This is why progress pictures are a great tool to assess how well you’re trimming down.

Here’s Karen before-after progress pics through the Flat Belly Firm Butt program as an example. Were she not measuring her belly and taking pics she wouldn’t have known that she was indeed making the type of #bodygoals progress (other than the fitness level increase of course which is easy to both measure and feel!) Learn more about how Flat Belly Firm Butt helped her no longer find exercise boring here.

Like bodyweight, you need to keep the conditions as consistent as possible for the best recordings. That means the same lighting, the same poses, and the same location of your progress picture. I suggest 4 poses: one front, one back, and one turned to each side.

Because, regardless of your diet or training programme, it takes time to see visual changes in your physique, you don’t need to take progress pictures that frequently. Once a week will do the job just fine, and provided your nutrition and exercise is in check, over the months you’ll see some amazing visual results.

I could tell you to do a body composition analysis but I won’t because it can also be very misleading.

Body composition

There are actually ways to measure body composition directly, so you know exactly whether you’re losing fat or gaining muscle. The bad news is that these methods are generally expensive and not very accurate.

That’s why I’m not going to spend a great deal of time on this as the most accessible and affordable methods to estimate the amount of fat, and muscle on your frame (ie: body composition) aren’t worth your hard-earnt cash.

1. Bioelectrical impedance analysis may tell you you’re fatter when you’re not.

This covers those fancy Tanita weighing scales that read out your body fat %, as well as the machines that you strap yourself up to with the use of cables and pads.

In short, they predict your body composition by firing a small electric current through your body. Because your body fat contains less fluid than fat free mass, it resists the electrical current more so than the other components of your body composition. The data relating to your bodies resistance to the current is then fed into equations that predict your body composition (fat % and fat free mass %) (9,10).

Thinking back to what I mentioned about fluid fluctuations earlier, can you think of any potential issues here?

Yeah, I thought so.

You see, because your hydration level can fluctuate so greatly, it can throw off the results quite dramatically. What’s more is the equations used to predict body composition are prone to screwing things up too.

So ultimately, there are lots of variables that can influence the number that bioelectrical impedance machines spit out. In fact, studies have shown that this method of estimating body composition and your fat % can be off by as much as 8% (9,11). That means you could lose a shed load of body fat, but the reading on the machine says otherwise.

For example, you might drop 4% body fat over a period of time, but the results of a bioelectrical impedance analysis could say you dropped nothing whatsoever. Or even worse, it might falsely say you put on 4% body fat.

So it’s best to steer clear of any tool that uses this method to assess body composition; their results could be wildly off, giving you a false impression of your progress.

2. Skin fold calipers can be useful in the right hands.

Body composition

Calipers are a similar story, being a bit hit and miss most of the time. Essentially they provide a means to estimate body fat levels by measuring the thickness of a number of pinched areas of skin.

The main problem here is the potential for human error, meaning that the reliability of their use is in the hands of whoever is taking your measurements (9). So if the calipers aren’t being handled by an experienced, well trained user, and if the same person isn’t taking the recordings each time, their results can be all over the place.

Similarly to bioelectrical impedance, the equations used to convert the data into a body fat % can also screw things up. So if you do go down the caliper route, make sure they’re being used by a well-trained expert and just use the raw skinfold thickness measurements as opposed to converting it into a percentage (9).

There are lots of other ways to estimate body composition, but most of the best methods (like DEXA) cost a small fortune to have done, and are pretty inaccessible to most of us.

Besides, the only way to actually measure your body fat levels is to directly weigh the stuff, and that would require you to be dead and then dissected.

Any volunteers?

Na; I didn’t think so.

So at the end of the day, you can only predict your body composition; not measure it directly (9,10).

Because of this, even the best methods to assess body composition have a 4-5% margin for error (12).

That doesn’t mean the above methods to assess your progress are pointless though; it just means you should be aware of their potential pitfalls and be as consistent as possible with your chosen method(s).

Scales measure weight. Weight is a proxy for fat. But it’s still only a proxy.

body composition weight

So don’t put all your eggs in one basket by relying on your scale weight only; it can’t measure your body composition. The scales might look like they’re saying you’re fatter or not progressing when the reality is very different!

Your weight might not drop due to natural daily fluctuations, your menstrual cycle, and/or because you’re building muscle. That doesn’t mean your diet and training aren’t working. In fact, in the latter scenario, it’s the complete opposite and the muscle that’s masking weight loss will actually make you look more toned in the long run.

Either way, the biggest take homes here are to:

  1. Understand when to take your scale weight with a pinch of salt as you diet, particularly if you’re looking at individual readings.
  2. That doesn’t mean you should stop weighing yourself. That’s up to you. The point here is to never rely on the scale alone because it can only measure weight as a whole and not fat and muscle mass.

So have you ever noticed changes in the mirror or in your clothes but not on the scale? Leave a comment below and let us know!

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  1. Hi, Tommy!

    Thank you for this very informative article.

    It’s good that you mentioned abut BMI. For the longest time, people worked hard for their “ideal” BMIs, but in recent years it has been concluded that it is not the best indicator of good health.

    Your clarification of proper weighing is also helpful. Many people are misinformed and they end up being frustrated after all their efforts

    Lastly, I would like to share that I personally rely on the jeans test. It may not involve any statistics but I consider it as a pretty accurate way for me to know if I am making progress.