174. How to Read Your Body Composition Data (And What to Do With It)

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What if you've actually been making progress, but just didn't know how to see it?

So many people feel stuck because the scale isn't moving, or because progress feels painfully slow. But total weight is only one piece of the picture. You could be losing body fat, building muscle, and moving in exactly the right direction… without even realizing it.

In this post, we look at how to use body composition data in a practical way, which numbers matter most, and how to avoid letting the data take over your life.

Why the scale does not tell the full story

Most people use total body weight as the main measure of progress. If the scale goes down, they feel successful. If it stays the same, they feel stuck.

But your weight does not tell you what is changing.

You could be losing body fat while maintaining or gaining muscle. You could be improving your metabolic health even if the number on the scale is not moving quickly. This is why body composition data can be helpful. It shows you more than just weight, and helps you understand what is happening underneath that number.

The numbers I care about most

A body composition report can include a lot of data, but these are the key numbers I focus on:

• Total body weight
• Skeletal muscle mass
• Pounds of body fat, sometimes called fat mass

Skeletal muscle mass matters because it is different from lean mass. Lean mass includes muscle, but it also includes other tissues and fluids. If we want to understand what is happening with muscle specifically, skeletal muscle mass is the number to look for.

Pounds of body fat helps show whether the changes are coming from the place we want them to come from.

If your weight has stayed the same, but body fat has gone down and skeletal muscle has stayed stable or increased, that is progress.

How to measure more accurately

Body composition scales are highly affected by hydration, timing, exercise, and food intake. To get the most useful data, try to test under the same conditions each time.

I recommend measuring:

• In the morning
• After using the bathroom
• Before eating or drinking much
• Before exercise
• At a similar time each time

If you test at very different times of day, the numbers may look dramatically different even if your body composition has not actually changed.

I also prefer scales with four points of contact, where both feet and both hands touch the device. These are usually more helpful than foot-only scales because they are not relying as heavily on assumptions about the upper body.

A few options I have personally used and recommend include InBody and Hume. 

Some DEXA scan locations may also be helpful, but make sure the report includes skeletal muscle mass, not just lean mass.

How often to check

You do not need to check body composition every day. In fact, that can make the data more stressful than useful.

A better approach is to check every four to six weeks. I generally would not check sooner than every two to three weeks because body composition takes time to change.

The goal is to look at the trend over time, not react to one isolated reading.

Helpful targets to watch

There are a few patterns I like to watch month to month.

• First, look at your rate of weight loss. You can calculate it like this:

Pounds lost ÷ starting body weight × 100 = percentage of body weight lost 

As a general guide, ongoing weight loss of more than about 1% of your total body weight per week may be too fast. Over a month, that would be around 4% of your total body weight.

• Second, compare pounds of body fat to pounds of skeletal muscle. 

A helpful goal for many people is for pounds of body fat to be lower than pounds of skeletal muscle.

For example, if you have 60 pounds of skeletal muscle, ideally your body fat would be 59 pounds or less.

Another helpful marker is whether skeletal muscle mass makes up at least 30% of total body weight. You can calculate it like this: 

Skeletal muscle mass ÷ total body weight × 100 = skeletal muscle percentage 

These are not the only markers that matter. 

Labs, symptoms, energy, strength, visceral fat, and how you feel all matter too. But these numbers can give you a clearer framework for understanding whether you are moving in a healthier direction.

What progress can actually look like

Progress is not always dramatic.

Sometimes people say, “Nothing is changing,” but when we look at the data, they are losing fat and gaining muscle. That is not nothing. That is exactly the direction we want.

Other times, people feel like things are moving too slowly, but the data shows they are losing almost entirely body fat while preserving skeletal muscle. That is meaningful progress.

Fast weight loss is not always better. If a significant amount of the weight lost is muscle, that is not the outcome we want. Slower progress that protects muscle and reduces body fat can be healthier long term.

Use the data as a compass

Body composition data is meant to guide you, not control you.

If your weight is plateaued, the data can help you see whether you are truly stuck or whether your body composition is still improving. If muscle is dropping, it may be time to look at protein, strength training, recovery, or whether weight loss is happening too quickly. If body fat is creeping up, you can catch it earlier and adjust.

But do not let the numbers run your life.

The goal is not to obsess over every report or chase perfect ratios. The goal is to understand your body better so you can make informed decisions.

Any movement toward better health matters. Better labs, more strength, improved blood sugar, more stable habits, better energy, and a healthier relationship with food are all signs of progress too.

Body composition data can be a helpful compass, but it should never become something that steals your peace.

If you want to go deeper on all of this, I created a mini course called Body Composition Decoded. It walks through every scenario, all the formulas, and how to actually read your reports month to month. I made it because this stuff genuinely isn't taught anywhere, and you deserve to understand what's happening in your own body. 

Note: In this episode, I also mention I’ve been using Folly Hair Growth Gummies. I had been taking them in the evening, but realized the B vitamins were too activating for me that late in the day, so I moved them earlier. If you want to check them out, I’ll link them here:

 Folly Nutrition Hair Health Gummies (Use code MATTHEA)

TRANSCRIPT:

Disclaimer: The transcript below is provided for your convenience and may contain typos, errors, or grammatical inconsistencies, as it has not been professionally edited or proofread. Please enjoy it as-is and read at your own discretion.

Please note: The content shared in this podcast and blog post is for informational and educational purposes only and is not intended as medical advice. Always consult your healthcare provider for personalized medical guidance.  

 Welcome back to another episode of the podcast. How are you all doing today? As I'm recording this, there's a massive thunderstorm outside. And am I the only one when it is raining cats and dogs, and the thunder is out that you just wanna read a book, and you wanna curl up on the couch? It's the middle of a workday, so I can't do that, but, it's interesting. I'm someone, I think back in the day I used to say, "Oh, rain," and nowadays I'm just like, "Oh, this is so cozy when this happens." So anyway, I have been, again, just getting my energy back these past few weeks. It is so nice that it's getting light a lot sooner in the morning. So I used to exclusively go and walk at that indoor high school walking track, and nowadays it is safe enough in the morning that it's not pitch black, so I can start to do my walks outside, which is so nice 'cause I love to vary my walking patterns and what I'm doing and how I'm doing it. I just refuse to walk in the dark because I don't need animals to come out at me. We have so many raccoons around here, and rabbits, and I don't even know what else. I do not need to have an early morning encounter with an animal, so I'm gonna make sure that there's light so I can see what's happening. Other true story here, so the past few days I had noticed, wow, I'm up a little bit later than normal, just a little bit. Instead of going to bed at 9:00, I was going to bed at 10:00. And then I noticed sometimes I was up in the middle of the night, and I was thinking, "Hmm, I had cut out caffeine several months ago now," and I was doing really great with my sleep because I'm massively sensitive to caffeine. Anyway, what I noticed, guys, is that you know those, the gummies that I was telling you about, the hair growth gummies, Folig? I was having them in the evening time, and I realized those B vitamins and things like that, it was just too late in the day for me. It was too activating. I know that I have done other multivitamins later in the day and it has not affected me like that. It makes me even more of a believer with the encapsulation technology that they use, that you're actually absorbing what you need to absorb. So anyway, long story short, I've moved it to much earlier in my day and now I'm fine. I love when stuff like that happens and you think, "Oh well, my sleep's just affected," and then you really think about it and you're like, "But this is the only thing that's changed." I like when things are effective, so I feel like for me, that's a really good sign. So this is gonna seem random, but this story relates just to show you how devil's in the details always with what you're working on. We've been watching recently at home the show "Gold Rush." There's a series that they have within it called "Mine Rescue," and it's really interesting. This show is all about miners that are trying to obviously extract gold, and they're not doing well. And so these two experts come in, and they help them with understanding the geology better, understanding their setup, like the way that their plant is built. Because it's really interesting in this industry, every single plant is different as far as how it's built. Some mines it's bigger gold, some it's more fine gold. So a- all of it's different. And the setups are really different if you, for example, are mining in a desert or if you're somewhere where the climate is colder. It's just all so different. If you haven't watched this show, typically Miners will sometimes dig really deep into the ground because they're trying to find a cut of earth where a riverbed has gone through it, because that will concentrate the gold. And so one of them, they say, "You know, we know it's here. Other people have been successful around us. We just can't get it to work." And so here's what they do. They call an expert from a mine that's not too far away, another person, and they come over and they say, "Yeah, we wasted years until we figured this out." So he looks at this maybe, like, 30 feet that they had dug. He's standing at the bottom of it, and he's looking up and he says, "Only that layer right there, those 24 inches," that's two feet, "those two feet are the only one that's gonna have gold in it. The rest is garbage." And I thought to myself as I was watching this, "Wow, this mine that isn't doing well, they're gonna go broke, and someone could come in for one minute and tell them exactly where to look and exactly what to do because they'd figured it out." And I was thinking about, isn't this the story with metabolic health, where you are just fumbling in the dark? You're just thing after thing after thing you're getting wrong, and then you find that one thing that helps you, and you think, "That was so easy. Why didn't I know that? Why didn't I see it? Why didn't I do it?" Well, guess what? It just wasn't the moment. It just makes me wax poetic for a moment that it really matters for you to know what you're looking for. And so today I want to go over just very briefly a few aspects of using one of these scale reports. So we call it body composition, they're the scales where you get readings about skeletal muscle, pounds of body fat, not just total weight. If all you can do is get a scale that has total weight, that's fine. I'm talking to people today that have scales that give a little bit more data. And I wanna talk what we're gonna look for in there that can be helpful over time. Number one, these scales are highly hydration dependent. You get up in the morning, you go to the bathroom, and you hop on this scale. You should not have just exercised for an hour. I literally just had a patient earlier this week that it looked like she lost nine pounds of skeletal muscle in the past three months, and there is no way. This woman is killing it with getting to the gym a few days a week with structured strength training classes, never done more, never been on a better track. And I said, "Well, when'd you do that test and when'd you do this test?" Radically different times of day. We just can't compare it. It's totally inaccurate. So you get up in the morning, you do this. There's a reason why I recommend some scales over others, when you have a scale where you are stepping with both your feet on it, and then you also have a part where both your hands are also touching a probe part, it's usually like a bar. There's like a cord that connects the bottom, up to that bar that you're holding onto. When you're doing that, you have four different touch points. These scales are what are called bioimpedance scales. It means that they are sending a little electrical current from one point to another. If you only have your two feet on it, it's gonna go from one foot to the other, and then it's using an algorithm to assume what the upper body looks like. Some people fit the norms and it's gonna be fine, but a lot of people don't, and so your data won't look right. That's why I really like when there's four touch points. There are several different companies at this point that are using great scales. I will just tell you the ones that I personally have tried. InBody, I-N-B-O-D-Y. I have used that for a long time. You can either buy it on Amazon, I'll put the link down below in the show notes, or you can go to inbodyusa.com. You can put in your ZIP code and you can find a location by you. They're not located in every single part of the country, so that might not work out for everyone. There are some DEXA scan locations. You need to make sure that they have the capacity to tell you skeletal muscle mass. Majority of the DEXA scan reports that I'm seeing just have lean mass, and so you're guessing what the skeletal muscle mass is, and we'll talk about that in a second. The other scale that I've personally tried, I've bought it for my home and used it and seen what it does, it's the Hume scale, H-U-M-E. And so that is more affordable, and they have a program where clinicians can get the scale at a reduced price for patients. That's been really helpful because it makes it more affordable for my patients. Again, I'm not in either direction sending you to any of these places. Just know that for my patients personally, we're using either InBody or Hume at this point. Okay, so now you have a time of day that's accurate when you're reading it. You have one hopefully that has four different probe parts, 'cause there are th- Renpho has a scale, a body composition scale like this. There's a lot of other ones that have things like this now. And the only things I care about are a few things. You're gonna get your total weight as you normally would, and then the only other two numbers that I care about are skeletal muscle mass, not lean mass, 'cause lean mass includes everything, skeletal muscle plus a bunch of other things. We just want skeletal muscle. And then also pounds of body fat, or it might say, fat mass. There's different ways of saying it. The things that I care about are, number one, how much per week or month are you losing total body weight loss-wise, so a percentage. Is it more than 1% per week? You might be going too quickly. In a month, let's say there's four weeks in a month, don't want you going over 4% total body weight loss. The first month or two can be different, but this is on average month to month to month going forward. That's the first thing I care about. Okay, number two I care about are your pounds of body fat less than your pounds of skeletal muscle? If you have 60 pounds of skeletal muscle, I want 59 or less pounds of body fat. Majority of people, when you reach that and then also where your skeletal muscle mass makes up 30% or more of your total body weight, when those two things are met, so your pounds of body fat are less than your skeletal muscle, and your skeletal muscle mass is at least 30% or more of your body weight, we'll put both formulas in the show notes, majority of my patients that reach that are then healthy. Now, of course, that's not the end of the story. We still look at labs, and I look at how someone's feeling, and we can look at visceral fat. We-- There, there's many things that we can look at. But most people, if we can get them to meeting those parameters- You're in a really healthy spot. This is something that I think it's helpful to look at month to month to month, what are the direction of how things are going? Remember, even maintaining weight is a hard thing. That's a win. But you could look at, very often patients will say, "Nothing's changing," and when we look month after month, they're losing fat and gaining muscle. That's not nothing changing. That's your body composition going in the direction that we want it to go or you might look at, you say, "Oh, things are going so slow," but you realize you are losing no muscle and you are 100% only losing body fat when you look at the numbers. That is incredible. I try with my patients to keep it 10% or less as far as skeletal muscle mass loss, and these are things that you can look at over time. And when you're realizing, "I'm stuck, I'm plateaued," you can try different strategies, and then you look every four to six weeks you hop on there. I would not do it sooner than two to three weeks because it takes time for body composition to change. You hop back on there and you see is it working what I'm doing, and if not, you pivot. What's really interesting is there's this data emerging that there's a percentage of people that regain weight on tirzepatide, and I'm not seeing that in my clinic. I've always wondered, like, why is that emerging from other people, but I'm not seeing it? And I'm convinced it's because we're monthly checking this data that I'm able to change things quicker with people so we're not having a 10, 20% regain. We are catching things right when they're starting to occur, and we're able to change things. So these are the few numbers that I really care about. So we'll have some of it written in the show notes. Now, if you're someone where you want to know a lot of different scenarios like, well, what happens when I'm sick and it looks like muscle mass goes down? There's all these different scenarios that are gonna make the scale look a certain way, but that's not really long term what's happening to you. I go through all of that in my mini course. It's Body Composition Decoded. I go through all of these scenarios. You can learn how to read this report month to month. You can have all the formulas written out. I think it's like a 60-page PDF, but I have, right in the middle of it, I have... What do I call this? I say, "Understanding pounds, percentages, and ratio: Body composition quick reference sheet." And I have on here all the formulas just one after another- Written out how to convert things over, examples of how to do it, so that you can literally just plug in your data and see how to look at it. I've been hearing from people that have gone through this course, I literally created it because it is taught nowhere. I had to go work with certain physicians to figure out how to really use these body composition reports in a way that was helpful. If it existed somewhere, I would I wouldn't have made a small course on it. And I've been hearing from people that have been doing the course how helpful it is that they finally understand what the numbers are. Even my patients that have done this course, they have said, "Oh my gosh, I understand more now what's happening. I know you've gone through this with me, but seeing it written out, it is so different," and then you can just come back to it at any time. If you wanna understand these things more, I think that would be a really great tool for you to use if that's something that you're looking for. I will put the link for this in the show notes, but it will be rentiaclinic.com/decoded, D-E-C-O-D-E-D. If you have struggled with your weight set point, your metabolic health, if you've struggled with this long term, you need to manage this for the rest of your life, and you cannot be reliant on someone for that to happen whenever I'm working with my patients, I love working with them, and honestly, I've been working with majority of them for years, and I love that. But what if one day I'm not there? They still know how to do this, and they can help themselves, they very much so know what's going on, and that's really important that you don't become dependent on someone. I have put all those different scenarios, all of that in that course. You can check that out if that's interesting to you. I do wanna leave with this comment: do not let the numbers run your life. Let it be a potential GPS, a potential compass in the direction that you wanna go, but do not let these numbers ruin your life. The reality is, any direction you go that leads to better health is an improvement. When I initially started this whole journey, I literally did not have my weight change, but I was evaluating my thoughts about food and why I was doing certain things and how it was happening. And then I started to make changes, and my weight did not change that much. I know it was less than 5%, but I reversed my pre-diabetes. And then after that, I was able to keep doing more, and it's been slow as can be, but here I am in a really different place because I just kept going, okay? I still don't have all the ratios where everything's perfect, I think that this work matters, but don't make it something where you can never be happy with the numbers that you see. Write down all the things that are going in the right direction for you and celebrate that, and don't be held hostage to these numbers. I think it's important to understand them, but don't let it run your life. Last parting comment, I forgot to say this in the beginning of this episode last week I talked just a little bit about my hair loss journey. So many of you wrote me back that you wanna hear more about hair loss, so I'm gonna be talking in two days here to Dr. Kamal Patel Sisodia. She's a triple board-certified endocrinologist that I've had on before. She is absolutely amazing, and there are so many other topics we could talk to her about, but we're specifically gonna speak to her about endocrine causes for hair loss. I think it's really important to look at the perspective. You hear a dermatologist talk about it. You hear an endocrinologist talk about it, and I'm gonna bring in several other people. When you hear these different perspectives, you get a really full picture of what can be going on, and then it helps you when you are thinking, "Well, who do I need to see?" or, "Have I had a full workup?" You really can make sure to advocate for yourself. Hopefully that is gonna be helpful coming up. I hope you all have an amazing rest of the week, and we'll talk soon.