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How To Slim Down A Muscular Upper Body

By Rachael Attard, Updated Dec 18, 2020

Last Updated on 16th March 2020 11:08 AM

I have spoken a lot about how to slim down thighs and bulky calves, but I haven’t talked too much about how to slim down a muscular upper body.

Most complaints I receive are still about muscular legs, as most women don’t seem to bulk up in their upper body as easy as they do in their lower body.

But it does happen – especially if you do a lot of heavy lifting for arms, back & shoulders.

This can cause your arms to become too buff for your liking, or you can pack some unwanted muscle mass on your upper back.

To be clear, of course, I’m not talking about bulking up in your upper body like a bodybuilder, but definitely getting your arms, back and shoulders to the size that is not to your own liking.

I have experienced my upper body bulking up waaay too much with heavy lifting and CrossFit, and I was definitely feeling more “buff” (especially for my small frame).

My back got really broad and my crop tops and shirts became really tight around this area, which left me feeling extremely self-conscious about my body.

If the same thing has happened to you, I have some good news!

You can get rid of muscular arms, big shoulders and a wider back and make your upper body smaller…but you need to follow a proper workout and diet regime for this specific goal.

In this article, I’ll share what exercises to avoid for slimming down a muscular upper body and what exercises you can do to tone up without getting bulky.

So, let’s dive in!


4 ways to slim down a muscular upper body

1. Stop The Workouts That Made You Too Muscular

”Use it or lose it!” Remember that golden gym rule? Well, it’s true.

Reducing any muscle takes time and requires you to not use these muscles and to give them a chance to reduce in size (or “atrophy”).

The easiest way to reduce the muscle size in your arms, back & shoulders is to stop working these muscles altogether and stop exercising for a while.

But you do not have to take such a drastic measure – you can achieve the same results if you change your workout routine to fit your fitness and body goals.

If you continue with heavy lifting (or whatever exercise that made you bulky), you will never reduce this muscle.

Stopping this type of exercise that got you there in the first place is the most important thing.

This means stop ALL direct resistance training that made your arms, back and/or shoulders bigger.

If you feel like your arms got bigger from 10 kg weights and bicep curls or overhead presses – these are out the window!

The same thing goes for the shoulder press – if this is what contributed to their growth.

Extra Tip:

Avoid any workouts that seem to “create a pump” in your target muscles and especially those that ”go to failure’‘.

I know giving up intense exercise and heavy lifting can be difficult at first (we can get pretty addicted to it), but there are lots of other exercises you can do (more on that, below).

2. Eat At A Slight Calorie Deficit

You can speed up the process by eating at a slight calorie deficit – and I really mean slight.

You do not want to mess up your metabolism by trying to go too extreme, as it will definitely hurt you in the long run.

I recommend eating 250-300 calories below your estimated daily intake for a few weeks and monitoring your progress.

This will help you lose weight and some of that weight will be muscle.

You do not want to go too extreme, because you will drop weight AND muscle overall.

Since muscle burns more calories than fat, having less of it slows down your metabolism, making it even harder to shed pounds in the future.

3. Eat a Ketogenic Diet

Very restrictive low-carb diets (aka ketogenic) restrict you to 25-30 grams of carbohydrates per day (or 5% of your daily calorie intake) and focus on very high fat intake while keeping your protein levels moderate.

These diets make significant muscle growth challenging according to multiple studies.

I’m a big fan of the Keto diet, as it can help you drop body fat, moderate blood sugar levels and (if you consume adequate amounts of protein) prevent too much muscle breakdown.

But there is a reason why bodybuilders don’t go full Keto (super low on carbs) – because it stops you from gaining too much muscle mass.

For more info on how to go Keto and what to eat, you can read my blog post where I explain this diet in detail.

But it’s extremely important that you don’t starve yourself.

That will just slow down your metabolism, and it may have serious consequences on your health. 

What About Protein?

I’ve seen advice online on how low protein diets would be the most effective ones for muscle loss.

I would not necessarily agree.

If a low-protein diet is paired with excessive cardio and high carb intake (while staying in a slight deficit), it will definitely lead to muscle loss…but there is a good chance that you will end up looking skinny fat.

Not to mention that high carb-low protein diets will most likely lead to insulin spikes which make this diet harder to follow in the long run.

Fat keeps you full, which is why eating below your maintenance levels will be easier to do while going very low carb.

These are the main reasons why I recommend going very high in fat while keeping the protein levels moderate – so you get a smaller upper body and leaner overall physique.

4. Do More Cardio

When I say cardio, I mean low to moderate intensity cardio, like lots of walking, running for 45 minutes or more or spending the same time on the elliptical.

Cardio (if done properly) does not necessarily lead to muscle waste, but it does help you drop body fat pretty quickly (especially paired with a calorie deficit) and help you slim down overall.

I do not recommend doing only cardio (again, because it can lead to looking skinny fat), which is why I would still do resistance training – but focus on the workouts that will keep you toned, not bulky.

More on that below.

Let’s first cover the exercises you should not be doing if you are too muscular in your upper body.


exercises to avoid if you want to lose upper body muscle bulk

As mentioned above, you need to stop doing the exercise/s that have contributed to your bulkiness. That is the number one priority.

Here are some workouts I’d recommend skipping for a while if you want to lose muscle from arms, shoulders and upper back specifically.

1. No Isolation Workouts For Your Upper Body

I would totally stop doing any isolation workouts that target your upper body muscles.

Isolating individual muscle groups, such as your biceps, triceps, and lats can lead to an increase in muscle size. 

If you want to get rid of the muscular arms, stop doing biceps curls, triceps press, hammer curls, and triceps kickbacks.

The same goes for rowing, shoulder press, bench press, lat pulldowns, and pull-ups. They work your shoulders, back AND arms.

2. No Overhead Pushing/Pulling Workouts

Steer clear of overhead pressing exercises, such as barbell shoulder presses and overhead pulling exercises, especially chin-ups and lat pulldowns.

Any overhead pushing/pulling motion will make your back broader, which might be an issue for you, as it was for me.

These exercises are used heavily in CrossFit, so if you are doing CrossFit and are getting too muscular for your liking, I would stop for a while.

3. No Lifting Very Heavy Weights

I would also avoid all heavy lifting and workouts focusing on low reps, high weights.

By this, I mean lifting anywhere in the 3-8 rep range.

There is a way to lift weights without getting too bulky, but if you want to get results faster, do not lift heavy for your upper body.


I would also highly recommend you to find out your body type.

This is super important since different body types lose weight and build muscle differently and 2 out of 3 body types can GAIN muscle very easily.

I’m a mesomorph body type which means I’m quite athletic and I can gain muscles pretty easily.

I didn’t know my body type when I started getting into fitness, but if I did, I could’ve saved myself much trouble.

If you are not sure about your body type, you can take my Body Type Quiz. It will help you learn your body type in just 2 minutes and it’s completely free. :)


how to train without bulking up your arms, shoulder or back

As I mentioned, if you want results super fast, the best way would be to stop training your upper body altogether.

But, if your goal is to stay active, there are workouts that will help you get a toned upper body without increasing the muscle mass on your arms, back or shoulders.

These are some workouts you can try that will help tone up your upper body without getting too muscular. Also, a lot of them are great for your core too!

I would suggest trying it out for a few weeks and seeing how your body responds to them.

If you feel like your muscles blow up even from these workouts, then you might want to focus on the lower body and full-body workouts (that don’t focus on the upper body much) for a while.


Boxing is one of my favourite workouts and I find it amazing for toning up your arms without adding bulk.

It tones them up really fast, and you only need to do 1-2 classes per week to notice a difference.

If you can’t get to a class, try making up your own little circuit at the gym (if it has boxing gloves and a bag), or doing a Les Mills Body Combat class at home.


Swimming is also really great for toning up your arms without increasing their size.

I know professional swimmers have really broad shoulders, but they do train ridiculously hard, which is why they have this shape. If you just swim 30 minutes 1-2 times per week, this won’t happen to you.

When I was into triathlon training, all I did was swim, cycle and run.

My arms were super toned and I wasn’t doing any resistance training for them. I was just swimming 2-3 times per week for 30 minutes.


You don’t need to avoid resistance training altogether. I would just avoid anything heavy, as I mentioned, and anything low rep (3-8 rep range).

I have posted a free lean arms workout on my blog, so have a look at this to give you an idea of some circuits you can do.

Also, I have posted a few free workouts from my  3 Steps to Lean Legs program.

These are all full-body so they will work your arms and core, as well as your legs. And it will give you a good idea of some exercises you can do that will tone you without causing bulkiness.


HIIT workouts are great for toning up and a lot of women don’t have issues with HIIT bulking up their upper body.

I normally advise endomorphs to stay away from HIIT workouts, as they are usually very leg focused and they can cause your lower body to bulk up.

If you think this is you, I would avoid too many lower body exercises and avoid too many shoulder pressing exercises.

Here are a few examples of HIIT workouts that won’t bulk you up.

A lot of core workouts also involve being in the plank position, and this is great for your shoulders and upper body too (without adding too much size on it).


Pilates is a great form of lighter resistance training that will tone up without adding bulk.

You can do regular pilates or reformer pilates – both are great. They use light weights, pilates rings or just bodyweight only.

As always, if you have any questions, please feel free to ask me :) I hope you found this helpful! xx


If you are looking for a full-body workout program that focuses on building a lean & toned body overall and slimming down legs, then you might want to check out my 3 Steps To Lean Legs program.

I created it specifically with the goal of slimming down bulky muscles on your lower & upper body, losing body fat and achieving a lean body.

I personally struggled a lot with finding a program I could do for a long period of time that wouldn’t make me end up looking too buff and muscular for my liking.

If this is something you have been dealing it, then I can wholeheartedly recommend it.

Here are results of one of my lean legs girls struggling with being too muscular.

slim down muscular upper body before and after
slim down bulky muscles before and after

My program comes with a diet regime (vegan plan available), workouts & cardio tailored specifically to your body type. And you get it for life.

If you’re interested in workouts only, then check out my FULL-LENGTH Workouts Video Course.


My last piece of advice is to be patient! Gaining those muscles took time and so will losing/reducing their size.

Sometimes, it can be even more challenging due to muscle memory.

But I can promise you this – if you make the changes to your diet and fitness regime, you will slim down your muscular upper body!

It worked for my clients and myself and it will work for you.


Rachael xx

Picture of Rachael

Rachael is an Australian born certified personal trainer and nutritionist who holds a Bachelor degree in Science.

After struggling for years to find an exercise and diet program that is tailored to women striving for lean and toned body with no bulk she designed her Lean Legs Program. This program is tailored to each body type and focused on helping women get toned but feminine bodies, without getting bulky.

Her mission is to empower women and help them stay in shape in a healthy and balanced way.

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99 comments on “How To Slim Down A Muscular Upper Body”

    Brook says:

    I do aerial silks but I’ve notice by arms have got bigger and my sports bras are tighter. Would this be because of the silks and should I stop it? I’m worried that if I stop doing what I enjoy, I will fall out of love with exercise altogether

      Lean Legs Support says:

      Hi lovely,

      You don’t have to completely stop doing something that you love. The key is a perfect balance and following the right workout and nutrition plan that will help you achieve your goals. If your goal is to slim down any bulky muscle, the best way to do it is by combining the right cardio and resistance workouts for your body type and adjusting your diet for weight loss. :)

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