How To Tell If You’re Losing Fat or Muscle

Your daily ritutal includes hopping on the scale, followed by excitement or disappointment. But hop off, sister. That scale doesn’t measure jack. Well, it measures one thing – how much your entire body weighs. It doesn’t measure how much fat you’ve gained or lost and it sure doesn’t tell you if you’ve lost or gained muscle. In fact, if you’ve simultaneously lost fat and gained muscle, the scale might not budge at all. Yet that’s tremendous progress!

To get an accurate picture of your progress, it’s better to use a combination of tools. If you’re trying to lose fat, you’ll want to make sure you’re not losing more muscle than necessary. Muscle is metabolically active tissue and can help you burn fat (plus it helps shape your body and makes you stronger!). Some muscle loss is inevitable when you decrease calories, but if you strength train you can slow that down or even prevent it. You’ll also want to know you’re losing fat, obviously.

If you’re trying to build muscle, you want to ensure you’re not also gaining fat. Building muscle requires eating more, which inherently increases your risk of gaining fat.


Using body fat calipers at home can give you an accurate picture of your lean body mass (LBM), which includes muscle, versus fat weight. This combo is commonly called your body composition. Neither the scale nor a tape measure can tell you if you’ve gained or lost fat or muscle (and how clothes fit or the mirror, while useful, are purely subjective). Using these tools together is just fine.  

Notice I said “estimate” your body fat. Taking your own body fat takes practice, and it will never be 100% accurate. You need to be able to live with it possibly being 1-3% off, typically. But that won’t matter, because you’re looking at the long-term picture. You’re looking for trends.

Trends are the money

Pretend you’re a red-tailed hawk flying way up in the sky (we see a lot of these in Colorado). You can see the whole landscape around you, including where you’ve already been and where you can potentially go to catch more tasty mice.How To Tell If You're Losing Fat Or Muscle

Now pretend you’re a red-tailed hawk with tunnel vision. You only see what’s in front of you, or maybe a little behind you and a little in front. You’re bound to continue repeating what you’ve already tried and making the same mistakes because you can’t see the whole picture.

That’s where measuring your body fat every 1-4 weeks comes in.

If you don’t like how your progress looked last week or month, you can change directions ever so slightly (or a lot if needed). This might mean more protein, fewer restaurant meals, less snacking, or more consistent workouts. Whatever it is, you first need to evaluate whether you’re losing fat or muscle and make changes appropriately. If you never check or rely on inaccurate methods, you might find yourself circling around the same little meadow over and over, rarely catching any mice.

We use the same principle for getting stronger using a training journal. For example, each week you refer to your journal to see if you can beat last week’s weight. You’re using the measurement of increasing the weight to get stronger.

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How often to measure?

Measuring your progress long term also helps you see trends that don’t include daily fluctuations. For example, if you relied on the scale every day to track your progress, you’d likely see fluctuations due to your pooping schedule, carb intake, water retention, and big meals, to name a few. Tracking your body fat every day would be ridiculous as well.

Estimating your body fat isn’t about obsessively worrying about what you eat or what you’re body’s doing. You need a longer term schedule (and at the same time every day) that will help you keep the big picture in view, while not waiting too long before catching issues.

A longer term view – anywhere from every 1-4 weeks – will tell you if you’re headed in the right direction. You’ve got to find your sweet spot. Does measuring every week make you obsessive about food? Then stretch it out, girlfriend. This isn’t about torturing yourself or creating more disordered thinking.

>> Learn how to track your body fat

So stop guessing about your progress. Tweak and track should be your mantra. If you just can’t make yourself do it or you feel overwhelmed, talk to me. I’m an online coach and weight management specialist. This is what I do – help women build muscle and lose fat in a straighter line. See you in nirvana.

This article first appeared on

10 thoughts on “How To Tell If You’re Losing Fat or Muscle

  1. I’m pretty sure generally you can be pretty sure that a majority of the weight you’re losing is fat as long as you’re eating enough protein and aren’t cutting weight too fast. Unless you’re really huge and muscular, your body is going to prioritize burning fat over muscle as long as you’re actually using your muscles.


    • Mark, you make a good point and I actually did read a study showing that leaner, more muscular people lose more muscle than people with a lot of extra fat. I know when I had a four-month layoff last year I lost a lot of muscle… Not that I’m huge, but probably more a factor of being lean. Thanks for writing!


  2. These are all great principles to keep in focus as you’re trying to lose fat – or eliminate debt – or just about any other goal you’re trying to accomplish. Thank you for sharing.


  3. With my point, first, make sure I’m losing weight by finishing the day with a calorie deficit. If I continue to lift and get a decent amount of protein, then basically all the weight I lose will be fat as long as I dont go on a massive massive deficit.


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