How To Tell If You’re Losing Fat or Muscle

You hop on the scale and it’s down – YES! But slow down, mama. How can you be sure you lost FAT and not MUSCLE?

If you’re thinking, “Who cares? The scale went down!” then we need to talk. You really don’t want to lose muscle while you’re cutting calories. Muscle is metabolically active tissue and can make you a fat-burning machine. If we don’t use it, we DO lose it. Plus muscle is just beautiful, you know? It shapes and sculpts your body and helps your clothes fit better.

How To Tell If You're Losing Fat Or Muscle | Workout Nirvana

So how can you tell if you’re losing fat or muscle? And if the scale goes up, how can you tell if you’re gaining fat or muscle? Muscle loss almost always happens with crash diets, but you can also lose muscle in a more balanced calorie deficit if you don’t strength train. (Gaining muscle will only happen if you lift weights. Just sayin’.)

Body fat testing will give you an accurate picture of both the muscle and fat in your body (your body composition). If you track it over time, you can see what’s REALLY happening. The scale cannot give you an accurate picture, and circumference measurements don’t reveal if you’ve gained/lost fat or muscle, either. You really need to use both of these tools with body fat testing to know the truth and the whole truth.

A Personal Example

I’ve tracked my own body fat and measurements consistently for the last three years. Most recently, I found that a few of my measurements were down. My initial, primitive reaction was, What the hell? How could I be losing muscle as hard as I train?? 

But when I checked my body fat using calipers and input the data into my nifty spreadsheet, I saw that I’d lost 2.1 pounds of fat and gained 1.1 pounds of muscle since October.

This would explain why my waist and thigh circumference decreased, but my biceps and shoulders had decreased too. Damn! But then I realized that I’d cut back on training those areas while I fixed a painful elbow and shoulder. It corresponded perfectly to the inches lost.

If I hadn’t realized that I’d actually gained muscle and lost fat overall, I might have been discouraged. But the picture is actually quite good! I’m motivated to keep pushing forward and make up for the losses.

Long-Term Trends and the Big Picture

Pretend you’re a red-tailed hawk flying far overhead (we see a lot of these in Colorado). You can see the whole landscape around you: Where you’ve been, where you’re headed, and where you might want to go. What’s ahead of you is the future; what’s behind you is the past. This 360° view is the big picture of your progress How To Tell If You're Losing Fat Or Muscle


It’s alright if you didn’t train last week because you were sick. But if you missed 5 out of 15 sessions, now, that will have an impact on your progress. Same with myself – two months of less intense training had an impact, but now I’m better and it’s time to push forward again.

When Tweaking Is OK

If you don’t like how your progress looked last month, you can change directions ever so slightly (or a lot, if you really need a readjustment). This might mean increased protein or more consistent training, focusing on the big lifts, or introducing some isolation movements. Whatever – you need to evaluate the cause of your good or not-so-good progress and tweak as you go.

If you’re serious about making long-term changes to your body, track your body fat, whether at home with calipers or at a Bod Pod (I did this last fall). Once every 6-8 weeks is fine, in my opinion, but you can do it more often if you like. I use a cool spreadsheet with myself and clients that calculates changes. It works!

So stop guessing about your progress. Tweak and track should be your mantra. If you cannot make yourself do it or you feel overwhelmed, talk to me. I’m an online coach and a personal trainer in the southwest Denver area. This is what I do – help women build muscle and lose fat in a straighter line. Connect with me with your questions or to explore working together. Or peruse my 300+ articles right here. Either way, I’ll see you in nirvana.

This article first appeared on

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  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 recently posted..Tips on What to Do To Build Lean MuscleMy Profile

    • 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. Great post, Thank you Suzanne

  3. 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.

  4. 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.
    Andy Nguyen recently posted..How to take Mass gainerMy Profile

  5. Excellent post,thank for sharing,Suzanne.
    Andy Nguyen recently posted..How to take Mass gainerMy Profile

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