How to lose muscle mass and get skinny

Skinny woman and how to lose muscle

Most folks at various points in their own fitness journey are usually looking to gain muscle.

They want to get stronger and look more athletic overall. Makes sense.

You also hear about people wanting to lose fat, which… duh.

But I want to talk about a different goal that sounds kind of odd at first, but is actually much more common than you might think.

How do you lose muscle mass on purpose?

In very brief and simple terms, here’s what you need to do to lose muscle mass and get skinny:

  • Eat at a calorie deficit
  • Do cardio
  • Eat less protein
  • Stop (or do less) strength training

Pretty simple.

Still, there’s actually a lot of factors to consider and a ton of different variations on losing muscle, which we’ll get into below.

(And be sure to check out my top recommended workout program for women who want a lean, toned physique)

But first:

Why would someone want to lose muscle mass?

I know, I know.

The idea runs so contrary to what many of us set out to do when we start training, but there are actually a ton of totally valid reasons for wanting to reduce your overall muscle mass, or to lose muscle in your legs or another specific body part.


  • You’ve been packing on muscle for a while and want to slim down for aesthetics
  • You want to decrease the size of a particular muscle group (say, your legs)
  • You need to alter your body type for a specific sport or activity

Fitness YouTuber Omar Isuf recently talked about how muscle mass in his arms was actually getting in the way of his form while doing Olympic style weight lifting, so he decided to stop directly training his arms in order to lose size there.

That’d be a sport-specific reasoning.

(You might be interested in how to lose muscle for running to improve speed or endurance.)

Or you might just decide you don’t really like the bodybuilder look and want to go for more of an “underwear model” type physique.

That’s totally cool.

You might not really like the way your muscles are fitting into your clothes, so you may want to lose muscle in your legs so jeans fit better, for example.

There are a ton of reasons for wanting to lose muscle, and they’re all completely valid.

So let’s dive in to how to do it:

Step by step guide to losing muscle mass

There’s really four things you need to do consistently to lose muscle mass:

1. Eat at a calorie deficit

This is the golden rule of losing any kind of weight and it holds true here.

Calories In Calories Out (or CICO) is the tried and true method for shedding mass of any kind. And it goes like this:

Everyone has a set level of “maintenance calories,” called Total Daily Energy Expenditure, based on his or her gender, age, weight, and activity level.

Basically, how many calories do you burn in a day just by existing?

If you eat roughly the same number of calories you expend in a day, you’ll neither gain nor lose weight. You’ll “maintain” your general body shape, size, and composition.

To gain weight (whether on purpose or just because you DGAF), you’ll have to eat at a calorie surplus, or at least a couple of hundred calories over your maintenance level.

To lose weight, you’ll want to eat a few hundred calories below maintenance. 500 or so fewer calories than your maintenance is a good and safe place to start.

You can calculate your own TDEE by using an online calculator like this one. Eat less than that to lose body mass.

2. Do cardio

This one is (maybe) optional, but can be an important tool in losing any kind of weight, even muscle.

Long and/or intense cardio workouts can burn a lot of calories, and will help keep you in the calorie deficit described above.

You’ll burn somewhere around 100 calories per mile running and roughly half that walking.

There’s also some evidence that fasted-cardio, ie working out when you first wake up and you have nothing in your stomach and no food energy to burn, can accelerate muscle loss.

3. Eat less protein

You probably already know that eating a lot of protein is a crucial part of gaining muscle.

There’s a lot of fancy reasons for this involving amino acids and such, but one of the biggest things to know is that protein contains nitrogen.

And when our bodies are in a positive nitrogen balance, they become capable of growth.

This is important because some people will argue that a high protein diet (and therefore a high nitrogen level in your body) can allow for muscle growth even while eating at a calorie deficit.

For this reason, if you’re looking to lose muscle mass, cut your protein intake.

But please be careful not to go too low.

0.36 grams per pound of bodyweight every day is the recommended amount, far lower than the amount usually recommended for building new muscle. That should be plenty low enough.

4. Stop (or do less) strength training

This is an obvious one. If you want to lose muscle, stop training your muscles!

(You should exercise if you’re skinny, however, you just might want to avoid too much strength training if you’re looking to avoid the muscular look.)

There are a lot of different factors that go into how long it will take for your muscles to shrink or atrophy after you stop training them, but be sure that it will happen if you’re not giving them the stimulus they need to grow or maintain their size.

(Somewhere between two and 12 weeks is normal)

If you want to lose muscle in your arms, stop doing arm work. If you want to lose muscle in your legs, stop doing leg work. It’s that simple.

Another thing to look out for, especially if you want to lose muscle mass in your legs, is to avoid things that might “pump” them up. That includes lifting weights but also things like riding a stationary bike or elliptical.

Stick to running or jogging.

And that just about covers it!

How to lose fat without gaining muscle

This is an interesting related question and might come to mind for people who want to get lean but are afraid of packing on size from strength training.

Your best bet here is to do much of what’s prescribed above:

  • Eat at a calorie deficit
  • Don’t strength train
  • Do cardio

If you stick to jogging and running, you won’t build much muscle over your body.

This kind of cardio mostly serves to keep you in a calorie deficit so you drop fat and muscle simultaneously.

How to lose muscle without losing strength

Well this is an interesting one.

But it makes sense if you think about it. Someone could want to lose muscle mass for any of the reasons listed above — say, they want to be more nimble on the soccer field.

That doesn’t mean they want to be weaker overall.

The best strategy for losing muscle mass without losing strength will be to do all of the above (eat at a calorie deficit, lower protein intake, and do cardio) BUT continue to strength train in the gym.

You’ll just alter your training a bit.

See, there is a such thing as ‘neural training,‘ and it’s what happens when you work with extremely heavy weight at very low rep ranges, like 1-3 reps per set.

Very little hypertrophy (muscle damage) happens in rep ranges that low, so lots of muscle regrowth is unlikely.

But the heavy loads are extremely taxing on your central nervous system and force it to learn to recruit muscle much more efficiently to accommodate the lift.

It’s possible to maintain strength or even get stronger by mostly training your nervous system: lifting very heavy for very low reps.

(Though without the right nutrition for recovery, it’s likely you’ll lose some strength while losing muscle mass. That’s life.)

Check out the Beachbody on Demand workouts (use my link for a free trial) to build a lean, toned body at home.

9 thoughts on “How to lose muscle mass and get skinny”

  1. Thanx! I want my muscles to shrink so badly, I could cry! I am doing HIIT at least 3 times a week and because of my body type (mesomorph), I became a more bulky version of myself. I am not BIG, but I don’t feel very feminine anymore. I am going to eat less protein, cut the HIIT a bit and start to jog more often. Thank you so much for doing this post.

    • Omg yes I feel the same way. I’ve always had a feminine frame but for some reason my muscles in my arms seem to get bigger. Which definitely isn’t my goal. I like to look more skinny and feminine.

    • Studies show that HIIT and sprinting can increase muscle mass without any other resistance training. Look at the difference between Olympic sprinters vs marathoners.To “shrink” your muscle think more “marathon” than sprint in your cardio training.

  2. Thank you so much for this article! It’s all about build muscle build muscle! well when you have a good muscle memory, you don’t need much to build muscle. The low protein statement was something I’ll look into!

  3. thanks so much <3
    i started to do strength training to get stronger for climbing but i bulked up so bad, which is not really fitting my goal (as i need to stay as light as possible while being as strong as possible). i will mainly focus on 1 and 3 as cardio is boring the hell out of me 🙂

  4. Great tips, I will try this. How ever, when I do cardio my body burn a lot of energy and it causes me to overeat. I will avoid doing strength training. The most important spot i will like to lean out, are my leg’s muscles (thighs).
    I strongly believe this tips will work out really well. Thanks

  5. I totally agree with you ladies. They lie to us, "don’t worry, Women can’t get big and bulky lifting weights." It’s a complete lie to sell gym memberships and supplements. I feel horrible now and want my pretty, feminine body back asap!!

  6. Good article. I’m thinking of trying the fasted cardio as well as reducing protein. Ordinarily i think it would be women who choose to lose muscle for appearance purposes, but i’m a guy and i have two reasons, both related. I am a self-teaching martial artist, been learning on my own for a long time now, and I want to build my body the way Bruce Lee did. he was well known for being physically stronger than people significantly larger than himself but also maintained the advantage of greater speed. see, when your muscles are smaller, but have the same pushing/pulling power, they are faster by default because it takes less effort to move one’s own body. i want that advantage and i also want to look that way. Bruce Lee has a physique that is enviable by anyone but especially martial artists because it just looks badass.

  7. I’ll give fasted cardio a try! I’ve been trying to lose both fat and muscle but I’m so heavy even jogging builds muscle on me and I jog almost every day.

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