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Losing fat and building muscle are two of the most common fitness goals. Unfortunately, the widespread desire to get fitter has also bred a lot of misinformation about what it really takes to improve your body composition. 

In this article, we’ll discuss nine body composition myths that we hear time and time again and the evidence that disproves them. 

Plus, we’ll give you some tips on how to actually reach the goals you’re working so hard for. 

9 body composition myths, busted

1. You can turn fat into muscle

Two people work out with ropes.

One of the most common misconceptions about changing your body composition is that the fat that you’re losing “turns into” muscle tissue. 

On the surface, this idea does make sense. Since your fat shrinks when your muscle mass is growing, it’s easy to think that the two are related. 

However, the process of body recomposition (aka building muscle while losing fat) is actually two separate processes: muscle growth and fat loss. 

Muscle growth, or muscle hypertrophy, requires resistance training and an adequate diet with plenty of protein. This allows your muscle tissue fibers to grow bigger and stronger over time. 

Fat loss, on the other hand, requires a negative energy balance. If you’re burning more calories than your body needs, your body then draws on your reserved energy stores — in other words, your fat tissue. 

While you can certainly lose fat and gain muscle at the same time, they aren’t inherently linked. Rather, they are two different processes that ultimately add up to your overall aesthetic and fitness goals. 

2. You can’t achieve your body composition goals without a calorie deficit 

A person holds a large bowl of salad.

If you’ve ever tried to lose weight before, you’re probably pretty familiar with the idea that you need to run a calorie deficit to shed pounds (in other words, burning more energy than you eat during the day). 

However, this is not a hard-and-fast rule for all fitness goals, including body recomposition. 

Gaining muscle (also known as muscle hypertrophy) requires plenty of protein, which helps your damaged muscle fibers repair and rebuild themselves faster than training breaks them down. 

In this case, a big calorie deficit would actually be negative since it might contribute to muscle breakdown if you weren’t also focusing on protein.

So, if one of your goals is to preserve your muscle mass while also losing fat, your focus should be primarily on having an adequate protein intake and doing enough resistance exercise, rather than depending solely on an extreme calorie deficit to change your body composition. 

A good resistance training program paired with an adequate but protein-rich nutrition plan will promote fat loss without causing you to lose muscle. 

3. You can reduce fat in specific areas of your body with targeted exercises

A trainer helps her client do sit-ups in a large modern gym.

This idea, also known as “spot reduction,” makes sense on a surface level. After all, if you’re working out a specific area of your body over and over again, it’s natural to assume that you should see progress on that area of your body right away. 

However, spot reduction is a myth. This comes down to basic human physiology: your Skeletal Muscle Mass (in other words, the muscles you’re working out) is located beneath a layer of body fat. 

As we’ve already discussed, the process of building muscle and the process of losing fat are two separate things. This means that working out those particular muscle groups with weight training will not reduce the fat located specifically in that area

You might see more muscle definition in the areas of your body that you work out most often, but this is because you’re building muscle there. You might also lose fat from an overall combination of exercise and diet that puts you in a calorie deficit, but you can’t choose where that fat loss happens

For example, let’s look at a study that evaluates the very concept of spot reduction. This study had participants do abdominal exercises for six weeks. 

The study found that the participants who did the abdominal exercises saw improvements in their muscular endurance, but the exercises didn’t make any significant difference to their body fat percentage, abdominal circumference, or body weight.

4. Cardio is the only type of exercise that can reduce body fat

A woman rides a bike outdoors.

Because fat loss is dictated by energy balance, it’s common to think that cardio is the best (or even the only) type of exercise that can help you lose fat. 

Many cardio workouts, like running, cycling, and swimming, are full-body exercises that require a ton of energy. As a result, cardio certainly burns a lot of calories, which is definitely good for losing weight. 

However, if you want to reduce your body fat while improving your overall body composition, you should also be doing resistance-training exercises

Building muscle helps increase your metabolism since muscle requires more energy to maintain. 

Evidence has even suggested that a combination of resistance training and calorie restriction was the most effective method for reducing fat

5. BMI is the best way to measure your fitness and overall health

Several dumbbells sit near a scale and a yoga ball.

BMI, or body mass index, is a measure of body fat that compares your current weight to your current height. This value does provide some useful information; however, there is a lot more to the story, which means that BMI on its own is not the best metric to watch if you’re trying to get healthier.  

While BMI does give you some general insights into the relationship between your height and your weight, BMI doesn’t tell you much about your body fat percentage at all. 

That’s because BMI can’t measure how much of your weight is made up of fat versus muscle, both of which are key indicators of your overall health and fitness. 

Furthermore, BMI also doesn’t tell you where your fat tends to accumulate, which is another important measurement you need if you want to understand your body composition and corresponding potential health risks.

These BMI limitations have given rise to a number of issues. For example, take the idea of being “skinny fat”, or someone who is technically at an average weight according to their BMI. 

A person with an average BMI can still have a higher body fat percentage than is optimal for their health — a fact which is masked by the simplicity of this measurement. 

Conversely, some people with a high percentage of muscle, such as athletes, may technically be considered overweight or obese by BMI standards while actually being in great shape. 

6. You need to do long, hard workouts every single day to make progress

A person wipes their face after working out, looking tired.

Hitting a body composition goal requires a lot of time, effort, and discipline. However, that doesn’t mean that you need to train hard every single day in order to achieve those results. 

In fact, your body actually needs regular rest periods! 

Giving your body a day or two to rest every week gives your muscles time to recover properly. Meanwhile, overexercising only increases your chances of burnout and risk of injury. 

What’s worse, doing too much training without accounting for rest can also hold your progress back. Overtraining syndrome, or working out too much without accounting for rest days, has been linked to fatigue, depression, and loss of motivation. It can even negatively impact your performance! 

So, to get the most out of your hard workouts, make sure to schedule a couple of days a week for active recovery. 

7. Eating at night makes you gain weight

People at a party grab finger foods.

It’s a common and long-standing myth that eating at night is a surefire way to gain weight. To be fair, the timing of your meals does seem to play a role in your metabolism.

For example, when paired with an adequate resistance training program, intermittent fasting has been shown to be effective for losing fat and maintaining lean muscle mass.

However, we can’t simply say that eating late at night will definitely cause you to gain weight. 

While research indicates that consistently eating large meals late at night can be detrimental, there is also evidence that consuming small and nutrient-dense foods at night can have some benefits, like maintaining muscle protein synthesis and heart health.

In cases like these, it’s more a matter of your pattern of eating rather than the timing itself. If you consistently find yourself eating large meals late at night and going above your desired calorie range, it might cause your body composition progress to slow down. 

That said, we can’t vilify night eating on its own without looking at all the other factors related to it.  

8. You can track body composition progress on a traditional scale

A measuring tape sits atop a scale.

We tend to get hung up on the number on the scale, but there are plenty of things that it doesn’t tell us. 

A traditional scale can mask your progress since fat tissue and muscle tissue have very different compositions. Muscle tissue is denser than fat tissue, which means that if you’re training hard, you might gain weight while actually losing fat and increasing your lean muscle mass

Conversely, relying solely on a traditional scale might hide other issues, such as muscle loss. In that case, lower numbers aren’t necessarily a good thing.

Instead of relying on the scale, you should track your body composition in other ways. 

For example, using a scale or device that measures body composition can give you a better understanding of how much of your weight is composed of fat versus muscle

Measuring your body composition regularly is also a good way to gauge your progress.  

9. Juice cleanses and detoxes can help you achieve your goals

A glass of fresh orange juice sits on the counter.

Mainstream diet culture often promotes “cleanses” or “detoxes” that are apparently designed to help you flush out fat, cancel out weeks of “bad” eating, and help you lose weight. These detoxes often involve supplements and juices rather than real food. 

Unfortunately, there are no shortcuts to a healthy body composition, which means that these cleanses and detoxes are not your best option. 

Any results you may see are very often temporary, with most people tending to regain any lost weight once they are off their “cleanse” and back to a normal diet. 

Cleanses can even be dangerous since they often involve extreme nutrient and calorie deficits or laxatives that can contribute to dehydration and dangerous electrolyte imbalances. 

Furthermore, there just isn’t enough evidence to suggest that a detox or cleanse does any “cleansing” at all. 

The bottom line 

Improving your body composition is often a long journey. To get the most out of it, it’s well worth taking the time to understand the basics of fitness science and dispel any myths you might have picked up along the way. 

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