18 Common Fitness Myths Debunked

Don’t touch the barbell, you’re going to get bulky. Do more crunches for a tighter waistline. Don’t rest if you want results. While these pieces of advice may be well-meaning, they’re just fitness myths.

Fitness myths that deserve to die. Once and for all. Because let’s be honest. Working toward your fitness goals, in and of itself, is challenging enough. The last thing you need is getting misled by fitness myths that hurt your progress. 

To make sure you’re on the right track, here are 17 of the most common fitness myths – debunked with science. 

#1: Lifting weights will make you bulky 

Take a look around the average gym – and you’ll quickly realize that getting big is challenging even for men. 

Men are, you know, supposedly better at building muscle because of their higher testosterone levels. Just a quick note, though: this is also a misconception. The truth is that despite our lower testosterone levels, women can gain the same percentage of muscle mass as men through strength training (1, 2). 

It’s just that men typically start with more muscle mass and strength in the first place. 

Alright. Back to our discussion of this fitness myth. As I said, putting on muscle is challenging. It’s a conscious effort. 

In addition to training consistently (while making sure to progressively overload), you’ll also need to eat in a calorie surplus. 

If you’re not eating more calories than you expend in a day, you won’t pack on significant muscle mass (3). Even if you’re heading to the gym 5 days a week. 

And even when you do everything right, muscle-building still takes time. Lots of it. How much, precisely? 

According to various studies: a humble 1% to 6% increase in muscle size per month (4, 5). To put this into perspective, imagine if your legs measure in at 51.5 cm today. A realistic increase in circumference (e.g. due to quad training) from 2 months of training would only be about 3 cm. 

Bottom line? Putting on significant muscle mass requires intention, planning, and dedication. You can’t get bulky ‘by accident’.  

#2: Lifting light weights for high reps ‘tones’ muscle

One of the most common fitness myths around: lifting light weights for high reps will ‘tone’ your muscles. 

Well, this fitness myth is just way off. To start, when sufficiently stimulated, your muscle fiber does one thing – and one thing only. Grow (6). It doesn’t get ‘toned’.

And more importantly, if you’re looking for a tighter physique (which undoubtedly involves muscle growth), here’s something to note. 

Muscle growth can occur with a variety of weights and rep ranges (7, 8, 9, 10).  As long as you increase training volume gradually over time, your muscles will have the reason to get bigger and stronger.

That said, this doesn’t mean that you should choose the lightest weight possible and simply perform 100 reps a set. 

In fact, you probably don’t want to go beyond 30 reps for any of your sets (11).

Doing so makes it more likely that central nervous system (CNS) fatigue will set in. And you’ll reach failure in a set prematurely before you even achieve full motor unit recruitment of that muscle group. Meaning? You’re reducing the effectiveness of your workout! 

Not to mention – those additional reps are going to extend your workout time significantly. Why subject yourself to a 2-hour session – which you could have completed in 45 minutes or less – when there’s no additional benefit? 

#3: The more you sweat, the better your workout 

The sweatiest workouts can feel like the most effective workouts. Surely ending your sessions completely soaked – and flushed – means you got a good workout, right? Well, not exactly. 

‘The more you sweat, the better your workout’ is yet another fitness myth. 

How much you sweat doesn’t correlate to the intensity of your workout. Or how many calories you’ve managed to burn. 

Why? It’s all got to do with sweat’s primary function: as a temperature regulator (12, 13, 14).  

See, when your body temperature rises (e.g. during exercise), your body produces sweat – and the evaporation of moisture from your skin helps to keep your internal temperature between 36.1°C to 37.2°C. 

In other words, sweating is simply the cooling temperature your body goes through to help you maintain a steady body temperature. 

Yes, in general, how much you sweat does tend to increase relative to the intensity of your workout. But it can also be affected by things like the temperature, what you’re wearing, and how well you’re hydrating. Which can all vary from workout to workout. 

Besides … every body is different. 

You might sweat a lot. Or you may hardly break a sweat. It doesn’t matter because it doesn’t tell you much about your workout’s effectiveness. There you have it: one of the most pervasive fitness myths around, debunked! 

#4: If you’re not sore, your workout didn’t count 

Feeling sore the days after a workout must be a good thing, right? You must have done something right. 

Contrary to what this widespread fitness myth says, not exactly. Research indicates that greater workout soreness does not necessarily translate to better muscle-building and/or strength-building results (15, 16, 17). 

Simply put, soreness is not an accurate indicator of your workout’s effectiveness. And research agrees. 

In fact, making muscle soreness your goal for every workout can be a bad thing. That’s because you’ll constantly be struggling to recover from sore muscles from the previous workout. This throws you off your training plan and reduces your training volume on the whole.

Instead of being hardcore, focus on consistency and progressive overload (i.e. increase training volume) with your workouts. Those are key to achieving good results with working out. 

#5: Lifting heavy weights is dangerous

You’ve likely heard that lifting heavy weights is dangerous. 

And have likely chanced upon (or even searched for) the numerous ‘gym fail videos of dislocated shoulders, herniated discs, and sprained ankles. 

Honestly, though, the idea that lifting heavy weights is dangerous is truly one of the least supported fitness myths around. 

In reality, you’re just as likely – if not more so – to get hurt doing other physical activities. 

Take this study published in the Journal of Strength & Conditioning Research, for instance. The researchers compared the injury rates across multiple sports, including (18):

• Strength training
• Soccer 
• Olympic weightlifting 
• … and more 

Guess what? You’re more likely to get hurt from playing soccer than from either strength training or Olympic weightlifting! 

If you’re still unconvinced, just know this: coaches regularly use strength training to supplement an athlete’s sport-specific regimen to help reduce the risk of sports-related injuries (19, 20).

While lifting weights is generally safe, there’s no denying that injuries can and do happen. 

That is why you should always take the time to learn proper lifting form. Hire a personal trainer if need be. As long as you’re performing the exercises correctly, strength training is still one of the safest sports you can do.  

#6: Weight machines are better than free weights 

If you’re new to the gym, one of the most common fitness myths (commonly masqueraded as lifting advice) you’d hear is to use the machines – instead of free weights. 

But they aren’t interchangeable options! Think about how your body moves with each of them:

• Machines: Fixed in place. Only moves in specific, pre-set directions (e.g. leg extensions, hamstring curls).

• Free weights: Can be moved in any way you choose (e.g. dumbbell bicep curls, barbell back squats).

So, it only makes sense that these options each deliver unique benefits. 

For instance, free weights are more versatile, allowing you to achieve a greater range of motion in any one specific movement. 

Another unique benefit of free weights? It’d be that it activates more ‘stabilizer’ muscle groups – which translates exceptionally well to functional movements (21, 22).  

As for the advantages that weight machines have to offer over free weights, it’ll have to be:

• Targets specific muscle groups better: Let’s say your ‘stabilizer’ muscles are fatigued after a round of squats – but you still want to work your quads. You can easily do so with leg extensions. 

• Provides guidance for the proper mechanics of a particular lift: If you’re new to a movement, a machine can help get you familiar with the proper mechanics. You’ll also get a better idea of where you should feel the exercise working.  

• Serves as an accessory for bigger lifts: Since your range of motion is fixed, you’re able to handle more load. This lets you work with heavier weights – which can help with bigger lifts like squats, deadlifts, and overhead presses. 

Bottom line? Ideally, you’ll want to incorporate both free weights and machines – just to reap each option’s unique benefits. 

#7: Cardio should be your focus when losing weight 

Want to lose weight as fast as possible? Just do more cardio. Best if you could do it every morning – and every night. Does this fitness myth sound familiar? 

First things first: yes, cardio can indeed help you burn more calories (although it’s probably not as much as you think it does). But no matter how many calories you burn through cardio, it’s pointless if you’re not eating a suitable amount of calories in the first place. 

When it comes to weight loss, only one rule applies. You need to eat fewer calories than you burn (23, 24, 25, 26). That’s called a calorie deficit.

Also, doing cardio exclusively is not an ideal approach. Not only is it boring, but it could also result in you burning fewer calories overall. 

That’s because strength training is crucial to building – and maintaining – muscle mass, which increases your metabolic rate (27, 28, 29). In other words: the more muscle you build, the more calories you burn.  And the easier it becomes to maintain a calorie deficit.

If you want to learn more about this, here’s an article comparing strength training and cardio for weight loss.

#8: HIIT is the ultimate fat-burner workout

Speaking of cardio … another one of those fitness myths that just won’t die relates to the idea that HIIT is simply the most effective form of cardio around. 

Supposedly, these shorter, more intense workouts can give you more results in less time. 

To understand why people believe this is so, you’ll first need to know something called the afterburn effect (also known as EPOC). EPOC is the amount of oxygen – and, thus, energy – your body needs to return to its normal, resting metabolic state. 

The more intense your workout, the more oxygen (and energy) your body will use up (30). 

That’s why HIIT is thought to help you burn more calories than your traditional steady-state cardio options. It’s more intense. 

Unfortunately, this afterburn effect is massively overstated. To illustrate this: at best, a 30-minute HIIT session will only burn 14 to 21 more calories than a HIIT session of the duration. 

Let’s be honest. You can burn that (and more) just by doing some household chores! 

For the final nail in the coffin for this fitness myth, here’s what a 2015 meta-analysis on the subject had to say: HIIT only has a ‘possibly small beneficial effect over steady-state cardio’ (31).   

Of course, this is not to say there is zero benefit to HIIT. 

Here’s an article on how much cardio you actually need where I dived deeper into how different cardio types stack up against each other.

#9: The shorter your rest periods, the better your muscle growth

Think that you’ll experience greater muscle growth with shorter rest periods? Unfortunately, it appears that you’ve fallen for one of the most common fitness myths around – but let’s debunk it together. 

Yes, cutting your rest periods can feel extremely satisfying. That pump. That soreness. It makes you feel like you’re getting the most out of your workout. 

In reality, though, you’re doing anything but. 

In fact, according to multiple studies, when your total training volume is equated, you’d experience more muscle growth with longer (3-minute) rest periods than short (1-minute) ones (32, 33). 

But why? Well, researchers suggest that when you cut down on your rest periods between sets, you’re more likely to experience higher levels of CNS fatigue going into the next working set (34).

This could compromise the level of motor unit recruitment you achieve, reducing the number of ‘stimulating’ (or ‘effective’) reps in each set. 

Thus, you should always ensure that you’re adequately rested before moving on to your next set. The critical thing to note is that no study has ever highlighted any downsides to more extended rest periods. 

Other than the fact that your workout will undoubtedly take longer to complete, of course. Concerned about a super long workout session? You don’t necessarily need to take a 3-minute rest period for every exercise. 

Here’s a rough guideline you can refer to (35): 

• Single-joint exercises (e.g. leg extensions, bicep curls): 2 minutes
• Heavy compound movements (e.g. deadlifts, squats): 3 minutes 

#10: Every muscle group deserves its own training day 

Monday is chest, Tuesday is glutes, Wednesday is shoulders … have you bought into similar fitness myths that you need to train your muscle groups separately – on entirely different days? 

Well. That’s not going to help you hit your optimal training volume, which depends on your lifting experience (36):

• Beginner: 6 to 10 sets per muscle group weekly 
• Advanced: 16 to 20 sets per muscle group weekly 

Doing 6 to 10 sets is pretty easy when you’re still a beginner. That just translates to 2 to 3 different exercises. But you’re going to eventually progress – and become an advanced lifter. 

That means you’d be looking at 5 to 7 different exercises for a single muscle group within a training session. That’s pretty challenging. And, worse still, research also shows that doing more than 10 sets per muscle group within a single session is counterproductive to muscle growth (37, 38)! 

Meaning? Instead of allocating each muscle group to a specific day, look into optimizing your workout routine such that your volume is distributed evenly throughout the week. 

In most cases, that’ll mean training each muscle group at least 2 to 3 times a week. 

#11: You can choose where to lose fat from 

Ah, here comes one of the heavily-peddled fitness myths of all time: spot-reduction. Take a quick look at the popular fitness YouTube videos. Chances are, you’re going to spot a trend in their titles:

• Flat stomach in 30 days
• Do these exercises to lose arm fat
• Slim down your thighs with this exercise 

Sounds familiar? I thought so. 

Unfortunately, though, spot reduction (i.e. the idea that you can ‘remove’ fat from specific areas of the body) is a myth. Studies have proven this over and over again (39, 40, 41). 

Why? Because your body doesn’t simply draw energy from the cells in the area you’re working. But, instead, it gets energy from the body as a whole. 

So all those leg lifts you’ve done in bed? They’re not going to do much for removing fat from the thighs. 

And worse still, being overly focused on one muscle group (e.g. hamstrings or the abs) can do more harm than good. It’s a recipe for muscle imbalances, which could set you up for some serious injuries down the road. 

So, what does this all mean for you?

If you’re looking to lose fat from a particular part of your body, you’re going to have to lose fat – overall. And that would involve sticking to a calorie deficit, which can be made slightly easier by:

• Staying physically active (e.g. cardio and strength-training) and 
• Making better dietary choices 

#12: Muscle turns to fat when you stop working out 

Um. How do I put this? 

When it comes to fitness myths, this probably tops the ‘most ridiculous’ list. See: muscle cannot turn into fat – and neither can fat turn into muscle. 

They’re entirely different tissues (42). 

If you strength train, your muscles get bigger via a process called hypertrophy (43). And when you stop?

The reverse occurs: atrophy. This is where your muscles simply become smaller. But … what about all those people who’ve put on weight after they’ve stopped going to the gym?

The same holds. Their muscles definitely did not turn into fat. It’s just that with their decrease in physical activity (coupled with a likely increase in food intake), they’re now more likely to be in a calorie surplus – which undoubtedly leads to weight gain (44, 45, 46, 47).    

It’s a sign of a change in body composition (i.e. more fat, less muscle). Not that of muscle being converted into fat. Bye-bye and good riddance, fitness myth. 

#13: Women need to eat less protein than men

To be fair … it used to be that nearly all the research relating to optimal protein intake is done with male subjects – which made this one of the trickier fitness myths to debunk. 

Thankfully, we’ve made progress on this front.

Recent research done on female lifters suggests the protein intake requirements are – in fact – not gender-specific. But instead, fat-free-mass-dependent (48). 

That means the more muscle you have, the more protein you’ll have to consume. Regardless of gender.

Admittedly, in light of this information, we can actually say that this ‘women need less protein than men’ fitness myth is a half-truth.

At the same bodyweight, men are generally leaner than women. And that, in turn, naturally translates to them having slightly higher protein requirements (49). Once again, though, this is not just because they’re men!

If we were to have a man and woman with the same:

• Bodyweight and
• Body fat percentage 

Then their protein requirements will be identical. 

#14: You need to consume protein right after your workout 

Some people sprint – like, at full speed – to grab their protein shakes right after their last rep. And that’s because they’ve bought into the idea of something called the ‘anabolic window’. 

Just so you know: this is supposedly a short time immediately following your workouts where your body is particularly primed to absorb nutrients (e.g. amino acids) and use them for recovery (i.e. muscle repair and building) (50). 

But notice the keyword: ‘supposedly’. 

As it turns out, the idea of your anabolic window being, well, a short window of time is nothing but a fitness myth. You have plenty of time to get your protein in after your training.

A recent 2020 review, for instance, indicates that muscle repair – and growth – takes place equally well whether you consume protein 1, 2, or even 3 hours after exercise (51). This is in line with an older review, which suggested that the anabolic window could persist as long as 4 to 6 hours after training (52)! 

So, it’s time to throw this fitness myth out of the window (sorry, the opportunity was too good to pass up!) 

Instead of pushing everyone aside at the locker room to reach your shaker bottle, you’d do best with simply ‘feeding’ your muscle tissues with decent doses of protein a few times (ideally 3 to 5) per day (53). All the while ensuring that you’re hitting your daily protein intake. 

Of course, there’s an exception to this. 

You will need to get protein into your system ASAP if you’re training fasted (54). That’s because fasting puts your body in a catabolic state – which means that consuming protein immediately after a workout is indeed crucial for reversing this state in your body. 

Other than that, the same old rules apply. 

#15: You should eat as little as possible to lose weight

A stick of carrot paired with kale smoothie for breakfast. Half an avocado for lunch. And for dinner: a slab of grilled chicken breast. 

Does that sound healthy to you? And yet … so many people believe in this fitness myth. That you have to eat as little as possible to lose weight. (It doesn’t help that many models’ ‘What I Eat In A Day’ videos look like this as well.)

But it is what it is: a myth. 

Yes, you have to eat in a calorie deficit. But you shouldn’t quite literally starve yourself! 

Why? Oh, where do I even begin? There are so many reasons – but here are the 3 major ones:

• It’s unsustainable: You can only sustain this extreme calorie-restricted diet for so long (55). The longer you restrict calories, the more likely you will end up bingeing – and then feel guilty about your binge. And you’re going to restrict calories again. It’s a vicious cycle. 

• Nutritional deficiencies: If you restrict calories over the long term, studies suggest that you can end up deficient in micronutrients such as iron, folate, and vitamin B12 (simply because you aren’t eating enough) – which can lead to anemia and extreme fatigue (56, 57, 58). 

• You risk muscle loss: The longer you stay in a calorie-restricted diet (and the more severe it is), the more you risk muscle loss (59, 60). Especially if you’re not eating enough protein and/or strength training (61, 62). 

So please, do not starve yourself just to lose weight! Instead,  calculate the right amount of calories you need to eat per day according to your unique needs. 

Yes, it’ll take some work. But you’ll see that it’s more than worth it. 

#16: Eating many meals a day boosts your metabolism

“If you want to lose weight, you’ve got to eat at least 8 times a day!” 

Right. Now, where have I heard this fitness myth before? Just about everywhere. Been following the general vibe of this article? Then you’d know that this is going to be debunked – just like the rest of the fitness myths thus far. 

So, let’s begin. 

To be fair, there is at least some level of science linking eating frequency and your metabolism. And it’s all got to do with something called the ‘thermic effect of food (TEF)’ (63). 

This is the phenomenon that your body has to burn calories to digest food (e.g. moving it through the digestive tract, extracting nutrients from food). It accounts for roughly 10% of your metabolism.

So, by eating more often, the supposed goal is to keep the TEF high throughout the day. Sadly, that’s not how it works. 

The amount of TEF is based on the total amount of calories you consume. Whether you eat 5 600-calorie meals or 3 1,000-calorie meals, your TEF is going to remain the same because you’re still eating 3,000 calories in total. 

Simply put, increasing or decreasing the number of meals a day does not change the number of calories burned (64). 

It has even been suggested that increasing meal frequency is more likely to result in a calorie surplus (65, 66).

#17: You need to eat carbs before strength training 

I’m going to be honest. I used to be a firm believer in this particular fitness myth. 

After all, it does appear logical and reasonable. Given that your muscles use the glucose from carbs as fuel, eating carbs before training has got to be a good thing … right? 

Surprisingly, research says no (67, 68, 69). 

It appears that pre-workout carbohydrate intake fails to improve resistance exercise performance (measured by total lifting volume) in nearly every study done thus far. 

And the reason why?

Well, it’s pretty simple. That’s because physiologically, if lifters are already eating adequate amounts of carbohydrates during their typical meals (i.e. breakfast, lunch, and dinner), then their muscle glycogen (i.e. glucose) stores would still be full going into their training bout. 

Now … does this mean you should skip out on your usual carb snack before your workout??

It depends. If you feel that you perform better with it, then, by all means, eat it. While evidence suggests that pre-carbohydrate intake wouldn’t improve your lifting performance, there’s also no data to indicate that it’d hurt it, either. 

Do what works for you – and puts you in the best state to train. 

#18: Training every day helps you achieve your goals quicker

Think of fitness influencers who post videos of their workouts – every single day. 

They never take an off day! And yet … they still look so good. Is there something we’re missing out on? When it comes to working out, is more really better for progress (be it for muscle growth or weight loss)? 

Psst: nope. 

The idea that you have to workout every day to realize quicker progress is just another one of the many fitness myths out there. Your optimal training frequency mainly depends on your lifestyle, training experience, and goals.

It’s not super helpful, for instance, to model your weekly workout routine after someone who’s prepping for a bikini show (i.e. specialized focus on muscle groups) if you’re just interested in ‘getting fitter’. 

Ultimately, the most important thing for you to do is to be reasonable and pragmatic with your fitness routine. 

How many times a week can you workout? Can you recover fast enough between workouts? And more importantly – can you sustain this for the long term? You don’t want to end up: 

• Overtraining: If you don’t take days off training, you’re not giving your body sufficient time to repair your muscles (70). You may end up in an ‘overtrained’ state, which undermines the effectiveness of your workouts. Excess fatigue, unusual aches and pains, and a decrease in performance are all signs that you’re doing too much. 

• Burning out: Doing too much too soon is a sure-fire way to experience psychological burnout – and lose your motivation to workout. And if you bail on exercising? You’re not going to see progress. At all. 

So, don’t think that failing to workout Monday through Sunday is a sign of ‘laziness’ or a lack of motivation on your part!

Don’t let fitness myths keep you from achieving your goals 

Many of these common fitness myths are so attractive and widespread simply because they sound logical and are easy to follow. If you’ve fallen for them (like I did before), don’t worry – that’s a lesson learned and one fitness myth out of the way.  

As with many things in life, it’s always good to dig a little deeper and understand the subject a little more before committing. Fitness is the same. Spend some time doing your homework and you’ll be just fine.

After all, fitness is something you’re going to be spending countless hours in your life. I think it’s worth the time and effort, don’t you agree?