How To Slim Down A Muscular Upper Body

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

In this blog post, I’ll first explain why some women (myself included) feel like their arms can get too muscly and shoulders too broad. I’ll also share how to slim down a muscular upper body, which exercises to do to tone up without getting bulky, and which to avoid.

WHY ARE MY ARMS SO BULKY? WHY DO I HAVE BROAD SHOULDERS? HERE’S HOW TO SLIM DOWN A MUSCULAR UPPER BODY

Most complaints I hear as a personal trainer are about muscular legs. Most women don’t seem to bulk up in their upper body as easily as in their lower body. For example, this study indicates that men have more muscle than women and that these gender differences are greater in the upper body.

When I lifted heavy, my legs bulked up first, but my trainer insisted I was imagining it, so I kept going.

I even added CrossFit to my routine.

After a few months of lifting and doing CrossFit, my arms and back started getting bigger. My tops felt tight even though I hadn’t gained weight, and I began feeling self-conscious about my body, too bulky for my liking.

I’ll be honest: I train to feel good and to look good. But when I lifted heavy, I didn’t like how I looked. And while many trainers won’t admit it, I don’t train just for strength.

I also know that a lot of women feel pressured to lift heavy and train solely to get stronger. It was the same for me. And this pressure and feeling like no one understands my fitness goals is exactly why I decided to take matters into my own hands and become a PT. I studied at the Australian Institute of Fitness and got Certificate III and IV. One of the decisions I ever made! ;) 

“BULKY” IS SUBJECTIVE

Since I became a PT, I have tried all kinds of different workouts and training styles. After a lot of testing on myself and learning a lot about fitness through formal education, I found what works best for women who are looking to get lean and slim down without bulking up.

To be clear, I’m not talking about bulking up like a bodybuilder — that’s hard to do. I mean gaining more muscle in the arms, back, shoulders, or legs than feels comfortable. “Bulky” is subjective — what’s bulky for me might not be for you.

And if you love having big muscles, that’s awesome! I’m not here to define your goals, if heavy lifting makes you happy, go for it!

And if you are someone like me who prefers a more slimmed and toned look, welcome to the Femme Nativa family. This is a community of women who train to both feel good on the inside and look good on the outside. And we promise you too can slim down a muscular upper body. 

You just need to follow a proper workout and diet regime for this specific goal. And I’m going to tell you exactly what you need to do. :)

HOW CAN I SLIM MY MUSCULAR UPPER BODY?

In order to slim down your upper body (arms and upper back), we first need to determine whether you should lose excess body fat, bulky muscle mass or both.

If you feel like your upper body is bigger than you’d like because you’ve gained weight (fat) AND muscle mass, keep on reading. If however, you know your arms and back haven’t gotten bigger due to training and gaining muscle, I recommend reading my blog on how to lose arm fat and get toned arms (without bulking up in the process).

OK so, what exactly should you do to slim down your muscular upper body? Below you have the biggest DOs and DON’Ts if you want to slim down muscular arms and a broad back.

1. STOP DOING WORKOUTS THAT MAKE YOU TOO MUSCULAR

If you take one tip from my guide on how to slim down a muscular upper body, let it be this one.

I’ve been there, told by trainers to “keep lifting heavier, your muscles will get smaller later.” Spoiler: they didn’t. The more I lifted, the bigger I got. And though I enjoyed it at first, I eventually realized it wasn’t the look I wanted.

If you’re not happy with how much muscle you’ve built, it’s okay to change your approach. Shift toward workouts that build endurance and lean strength, like power walking, bodyweight moves, and light weights (5–10 kg). You’ll feel and look more balanced.

EXERCISES TO AVOID IF YOU WANT TO REDUCE MUSCLE MASS FROM YOUR UPPER BODY

As mentioned above, if you want to slim down a muscular upper body, you need to stop doing the exercise/s that have contributed to bulkiness. That is the number one priority.

Here are the workouts I’d recommend skipping for a while if you want to slim down your upper body, specifically to lose arm muscle as well as to slim your shoulders and back.

1. NO ISOLATION WORKOUTS FOR YOUR UPPER BODY

Stop doing isolation exercises that target your upper body, like bicep curls, shoulder presses, lat pulldowns, and tricep kickbacks. These moves build size in specific muscles such as your biceps, triceps, shoulders, and lats.

If your arms have bulked up from these workouts, take a break from them until your muscles slim down to a level you’re happy with. Then, reintroduce them occasionally using lighter weights and higher reps.

2. NO OVERHEAD PUSHING/PULLING WORKOUTS

Overhead pushing and pulling exercises can make your shoulders and back broader — something many women, myself included, want to avoid. These movements, like shoulder presses, chin-ups, and lat pulldowns, tend to add upper-body bulk.

If they’re causing you to build more muscle than you’d like, take a break from them to let your shoulders and back slim down. Since these moves are common in CrossFit, consider pausing that style of training if it’s making you too muscular for your preference.

3. AVOID LIFTING HEAVY WEIGHTS

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

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

There is a way to lift weights without getting bulky. But to really slim down your upper body, you’ll need to avoid lifting super heavy weights. 

DO I REALLY NEED TO STOP LIFTING WEIGHTS IF I WANT TO SLIM DOWN A MUSCULAR UPPER BODY?

I’m not saying you should remove resistance training completely from your routine. Every good workout routine should include resistance/strength training. But there are ways to do resistance training without heavy weights. 

If you’re not sure what resistance training is, I’ll explain below. 

Resistance training, or strength training, uses weights, bands, machines, or even bodyweight to build and strengthen muscles.

While stopping resistance training altogether can reduce muscle size in your arms, back, and shoulders, I don’t recommend it. You can get the same results by simply adjusting your workouts to match your body goals.

BONUS TIP – HOW TO LEARN YOUR BODY TYPE & HOW TO SLIM DOWN A MUSCULAR UPPER BODY SO YOU CAN ADJUST YOUR DIET & WORKOUT

I would also highly recommend you 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 muscle (and fat) pretty easily.

I didn’t know my body type when I started getting into fitness. But if I did, I could’ve saved myself a lot of trouble. It’s important to work out according to your body type to not make the same mistakes I did.

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. :)

2. HOW TO EAT AT A SLIGHT CALORIE DEFICIT

If you want to slim down a muscular upper body, 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. 

Eating a very low-calorie diet (anything below 1200 is considered low for an adult woman) can cause nutritional deficiencies, increase your risk of gallstones, impact your bone health, and increase the risk of cardiovascular risk, just to name a few.

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. But as I mentioned, you really do not want to go too extreme, because it will backfire in the long run.

If you are not sure of your ideal calorie intake and how much you should eat to be at a slight calorie deficit, you can use my free calorie and macros calculator.

3. HOW TO SLIM DOWN A MUSCULAR UPPER BODY: TRY SWITCHING TO A LOW-CARB (MODERATE PROTEIN) DIET

Low-carb diets typically involve reducing carbohydrate intake significantly compared to a standard diet. The specific daily carbohydrate limit can vary, but it’s generally in the range of 20 to 150 grams of carbohydrates per day.

According to this study, low-carb diets, like the ketogenic diet, for example, help with fat loss but also make significant muscle growth challenging. This means it’s harder to bulk up while eating low-carb. 

Based on the studies I’ve read, like the one above and based on my education as a nutritionist, I believe that low-carb diets can be very beneficial for women who want to lose weight and get lean. 

SHOULD I CUT ALL CARBS FROM MY DIET?

No, you shouldn’t cut out all carbs. Your body and brain need them to function properly. Cutting carbs completely can cause your body to break down too much muscle for energy — and while you may want to reduce bulk, you still need some muscle to stay healthy and toned.

Go low-carb, not no-carb. Focus on carbs from fruits, vegetables, and occasional whole grains — they’re rich in fiber and nutrients.

And remember, balance matters: keep enough protein and healthy fats in your diet, even when aiming to lose muscle bulk.

RELATED POST: IS THE KETO DIET GOOD FOR YOU?

BUT WAIT, WON’T PROTEIN MAKE ME BULK UP?

A lot of my clients ask me if they should eat less protein to reduce their muscle size or prevent their muscles from getting too bulky. And I get why they are asking.

Protein is an essential nutrient for muscle repair and growth, and it plays a significant role in the recovery process after exercise.

Protein helps with muscle repair and recovery, but it doesn’t make you bulky.

Muscle size comes from your training style, not your protein intake. Heavy lifting and training to failure build more mass, while lighter, high-rep workouts create a leaner look.

As I said, protein just helps the muscles repair. Plus, the body has a limit to how much protein it can use for muscle building, and any excess protein is typically metabolized for energy or stored as fat.

If you want to avoid bulky muscles, adjust your workouts, don’t cut back on protein.

A low-carb diet with moderate to high protein can help reduce excess muscle while supporting recovery.

RELATED POST: WHY YOU NEED PROTEIN FOR WEIGHT LOSS

4. DO MORE EFFECTIVE CARDIO

If you want to slim down a muscular upper body,  I would highly recommend doing effective cardio.  A lot of women who bulk up from too much weight training often have one thing in common. They avoid cardio. Usually, they avoid it because they have heard “Cardio is useless, it doesn’t help tone your muscles”, and there are lots of personal trainers and fitness influencers out there that are anti-cardio. 

However, recent research on the effects of cardio on muscle shows that cardio (aerobic activity) combined with resistance training can actually promote building of lean muscle mass. And this is exactly what most women are after – lean and toned muscle. Plus low-intensity steady-state cardio (such as walking) also burns fat which will help even more with achieving a leaner look.

If you read any of my most popular blog posts, you probably already know that I’m a huge advocate for cardio. :)  Not only does it help with staying lean and weight loss but research shows that it also has a ton of other health benefits – reduces your risk of heart disease, diabetes, high blood pressure, and high cholesterol.

LONG-DURATION, LOW TO MODERATE-INTENSITY CARDIO IS YOUR FRIEND

So if you want to be lean and toned (and healthy!), effective cardio should definitely be a part of your routine.

What do I mean when I say effective cardio? 

When I say effective cardio, I mean long-duration and low to moderate-intensity cardio. A good example of this type of cardio would be:

• Walking
• Running
• Swimming
• Elliptical

For the cardio to be the most effective, I recommend doing it for a minimum of 20 minutes (or more), 4-5 times per week.

Cardio alone isn’t enough if you want a toned body, you need to combine it with resistance training. Without strength work, you risk becoming “skinny fat,” meaning slim but lacking muscle tone and definition.

To stay lean, lose fat, and avoid bulkiness, mix cardio with resistance training that builds tone, not size. I’ll share the best upper-body exercises for that below.

RELATED POST: WHAT TO DO IF YOU ARE “SKINNY-FAT”

5. FOCUS ON EXERCISES THAT WILL TONE YOUR UPPER BODY WITHOUT BULKING UP – HOW TO DO IT

As I mentioned, if you want results super fast, you could stop training your upper body altogether. But I wouldn’t really recommend that. 

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 bulk up even from these workouts (it could potentially happen if you are an Endomorph body type and you bulk up super easily), then you might want to focus on the lower body and core workouts (that don’t focus on the upper body much) for a while.

BEST EXERCISES TO TONE YOUR UPPER BODY WITHOUT BULKING UP

1. BOXING

Boxing is one of my favorite 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. Plus it’s great for your fitness too!

2. SWIMMING

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 20-30 minutes 1-2 times per week, this likely won’t happen to you.

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

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

3. BODYWEIGHT RESISTANCE TRAINING

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 a couple of free upper body workouts on my blog, so you can check them out to give you an idea of some circuits you can do.

Also, I have posted 3 free workouts from my Lean Legs Program 1.

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

• Free Lean Legs Workout – Day 1
• Free Lean Legs Workout – Day 2
• Free Lean Legs Workout – Day 3

BONUS TIP FOR SLIMMING DOWN A MUSCULAR UPPER BODY – HIGH REP VS TRAINING TO FAILURE

Avoid training to failure and focus on high-rep workouts instead, I’ll explain why below. :)

Training to failure means pushing an exercise until you can’t complete another rep with good form. It’s great for building size but not ideal if you want to stay lean.

High-rep training uses lighter weights and more repetitions to build endurance, improve tone, and avoid muscle bulk.

It can be tough to step away from heavy lifting at first, but there are plenty of effective alternatives you’ll enjoy.

RELATED POST: THE FEMALE GUIDE ON HOW TO GET LEAN AND NOT BULKY

4. DO HIIT WORKOUTS (THAT WON’T ADD BULK)

HIIT workouts are great for toning up and a lot of women don’t have issues with HIIT bulking up their upper body. HIIT also burns a lot of calories and increases your fitness.

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 are an Endomorph and you know you bulk up very easily, I would avoid doing 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:

• Full Body HIIT Workout That Won’t Cause Bulk
• 15 Minute HIIT Ab Workout

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).

Try this quick plank series to tone your upper body.

 

 

 

 

 

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5. FOCUS ON PILATES STYLE TRAINING

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, balls, bands or just bodyweight only and are very unlikely to bulk up your upper body. 

6. HOW TO DO A FULL BODY WORKOUT PROGRAM THAT WON’T ADD ANY EXTRA BULK

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 Lean Legs Program 1.

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 with, then I can wholeheartedly recommend it.

My program comes with full-length workout videos tailored specifically to your body type. And you get it for life.

7. BE PATIENT

My last piece of advice is to be patient! Gaining those muscles took time and so will losing/reducing their size. It takes longer to slim down muscle than it does to gain muscle.

When I bulked up from lifting weights, it took me around 6 months to get back to a size where I felt comfortable. 

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.

Love, Rachael xx

SOURCES:

• Body Muscle Mass – Men VS Women – https://pubmed.ncbi.nlm.nih.gov/10904038/
• CrossFit – https://www.crossfit.com/what-is-crossfit/
• Very Low-Calorie Diet risks – https://www.webmd.com/diet/low-calorie-diets
• Low-Carb Diets and Weight Loss – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7911670/
• Protein For Muscle Repair and Recovery – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6142015/
• Too Much Protein – https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/are-you-getting-too-much-protein
• Effects of Cardio on Resistance Training – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4523889/
• Aerobic Exercises Benefits – https://my.clevelandclinic.org/health/articles/7050-aerobic-exercise