Does muscle weigh more than fat?

Most of us are familiar with the fundamentals of weight loss. From burning more calories than we consume to entering a calorie deficit, a sustainable weight loss journey means reassessing all aspects of your lifestyle.

Even so, it’s hard not to become obsessive with the scale — especially if you’ve set yourself a goal weight to achieve. 

But while the numbers on the scale can prove helpful for tracking your progress, they aren’t always reflective of overall health. If you're seeing a change in body fat percentage but not on the scale, you may have found yourself asking: does muscle weigh more than fat?

While muscle and fat weigh the same, a vital difference exists between muscle density, fat mass, and body composition.

It’s an important distinction to make, particularly when so much of our motivation can be tied up with seeing results. So, if you’re  wondering why the numbers on the scale won’t budge, you’ve come to the right place.

Below, we’ll break down the difference between fat vs muscle, how it impacts your weight, and why gaining muscle mass is key to losing fat no matter your weight loss goals.

Fat vs muscle: What's the difference?

We all know that the key to sustainable weight loss is to adopt healthy habits, from incorporating daily exercise and strength training into our lifestyle to eating a balanced diet of nutrient-rich foods.

But if you’ve started going to the gym to lose weight, you’ve likely heard the myth that “muscle weighs more than fat” thrown around. 

The reality is that both muscle and fat weigh the same, but there’s a huge difference between the two in terms of density.

With a higher density than fat, muscle takes up less space than an equal amount of fat. Think of the difference between a pound of cotton balls and a pound of steel; they may weigh the same, but the latter takes up far less space than the former. 

It’s this difference that has a profound impact on body composition.

Two people can weigh the same, but depending on the distribution of fat and muscle in their body, they will look noticeably different. For example, someone with a high percentage of lean muscle mass will look slimmer and more toned than someone who weighs the same but instead has a high percentage of fat and less lean muscle. 

Another key difference is that muscle is more metabolically active than fat, meaning muscles burn more calories than fat — even at rest.

As a result, more muscle mass can contribute to your total daily calorie burn. Whereas fat burns roughly 2 calories per pound, studies have shown that a pound of muscle burns up to 7 additional calories per day [1].

Is muscle heavier than fat?

Despite the popularity of the myth that muscle weighs more than fat, it doesn’t.

Ultimately, a pound of muscle and a pound of fat weigh the same. So, while there’s no truth to muscle being heavier than fat, they do have a distinctly different effect on body composition. 

It’s an important difference to understand as it’s one you won’t see reflected by the number on the scales.

Though two people might weigh the same, researchers have found that those with a higher percentage of body fat have a higher overall death rate, regardless of body mass index (BMI). This is because fat increases your chance of developing conditions like hypertension, diabetes, and heart disease [2].

Therefore, it’s important to focus not so much on the scales but rather on how you feel and the changes to body composition.

Someone with more lean muscle mass will not only decrease their risk of obesity-related conditions but will also improve their bodily functioning. According to a 2019 study, exercise has an anti-inflammatory effect, improving immune regulation and delaying the onset of age-related dysfunction [3].

4 possible reasons why you look thinner but weigh more

If you’re weighing yourself only to find that the number is either not budging or increasing, yet your clothes fit better and you’re looking thinner, then you’re likely seeing muscle gains.

If you’re seeing noticeable changes, particularly around the hips, thighs, belly, and arms, you’re likely reducing body fat and increasing muscle mass. 

To ease some of your concerns about the number on the scale, here are 4 possible reasons you may look thinner but weigh more:

1. You’re gaining lean muscle mass

Signs of muscle gain include a decrease in body fat percentage and a leaner physique, strength improvements in the gym as a result of lifting heavier weights and performing more repetitions, and an inability to shift the scales.

For the latter, in some instances there might even be an overall increase in body weight, however, you’ll find that you lose inches around certain body areas. 

2. You’re weighing yourself at the wrong time

Weight changes throughout the day, depending on how frequently you’re eating, how much you’re drinking, and how often you go to the bathroom.

For a more accurate measurement, be sure to weigh yourself first thing in the morning.

3. You’ve increased your cardiac output

If you’re exercising frequently and doing cardio, you can expect to see an increase in blood volume, which equates to higher cardiac output. This increase in fluid can also contribute to weight.

4. Your body composition is changing

If you’re losing fat in certain areas and gaining muscle, the shape of your body will change. You’ll appear thinner, with a leaner appearance and muscle tone, but you won’t see this reflected on the scale. 

How to measure your body composition

Unlike the number on the scale which simply tells you how much you weigh, your body composition tells you what your weight is comprised of in terms of the percent of total body fat and lean muscle mass.

While there are a number of ways to measure body composition, it’s worth noting that the most accurate measurements aren’t available at home. 

Here, you’ll find the best methods of body composition measurement: 

Skinfold callipers

Skinfold callipers measure the thickness of subcutaneous fat — the fat underneath the skin — at several body locations.

Typically, 3 or 7 different sites on the body are used for measurements. For women, these are the triceps, the area above the hip bone, either the thigh or abdomen, as well as the chest, the area near the armpit, and the area beneath the shoulder blade for a seven-site measurement. For men, it’s the chest, abdomen, thigh, armpit, and beneath the shoulder blade. 

Body circumference measurements

By measuring the circumference of certain body parts, you can get an estimation of body fat.

For men, the circumference of the neck and waist are used and for women, the circumference of the hips is also included. 

Dual-energy X-ray absorptiometry (DXA)

This method uses X-rays of 2 different energies to estimate body fat percentage and bone density. You’ll receive a detailed review of bone, lean mass, and fat in separate body regions.  

3D body scanners

By using infrared sensors, a 3D body scan provides a detailed view of your body composition.

Equations will estimate your body fat percentage based on body shape in a way that is similar to circumference measurements, albeit more detailed. 

5 tips for losing fat and gaining muscle mass

With all the benefits that come from increased muscle mass, here are 5 tips to help you see muscle gains while losing fat.

1. Incorporate resistance training

Exercise is an essential part of a healthy lifestyle, but to lose fat and gain muscle mass, you need to make resistance training a priority.

To gain muscle mass, you need to enter muscle hypertrophy by challenging the body, gradually increasing the weights and lifting heavier as your body adapts to resistance. 

In a 2011 study that analysed 83 people over 12 weeks as they performed a series of arm strengthening exercises, it was found that both men and women who gradually increased the weight and number of repetitions of exercises were able to see an increase in bicep strength and muscle growth [4].

By placing greater demands on your body with an increase in weights, you overload muscles and allow them to make further adaptations. 

2. Eat carbohydrates before exercising 

Diet culture has been particularly unkind to carbohydrates, but they play a key role in muscle building. Carbohydrates can also increase energy levels and workout performance and help with muscle recovery. 

When it comes to carbohydrates for fat loss, the key is to eat them at a specific time — ideally, before your workout.

This will help keep your glycogen levels high so you can avoid fatiguing quickly. And, because you’re working out, you’ll use up the carbohydrates consumed, so you don’t need to worry about weight gain. 

3. Focus on protein 

To lose fat and gain muscle mass, you need to eat protein.

As well as helping with muscle gains, it has a relatively high thermic effect compared to carbohydrates and fats, meaning the body requires energy to digest and absorb protein. Approximately 20-30% of the calories in protein are expended during this process. 

According to a 2016 study, a dietary protein intake higher than the recommended dietary allowance saw subjects preserve lean muscle mass, even when in a calorie deficit [5].

Throughout the 4-week trial period, which saw all subjects perform resistance exercises and high-intensity interval training, those consuming a diet high in protein managed to both increase lean muscle mass and fat loss. 

When it comes to foods that support fat-burning and muscle growth, choose the following:

• Lean meats like chicken, turkey, and lean beef
• Fish and seafood like salmon and tuna
• Greek yoghurt and cottage cheese
• Plant-based protein sources like tofu, tempeh, and legumes
• Whole grains like brown rice, quinoa, and oats
• Sweet potatoes
• Fruits and vegetables
• Nuts and seeds

4. Stay hydrated 

Given that muscle is comprised of around 75% water, it’s important to stay hydrated, especially after a workout.

As well as increasing circulating blood volume to allow for enhanced delivery of essential nutrients for muscle repair, hydration is also important to remove waste products that accumulate during exercise. The other benefit is that it can help curb appetite, as your body can’t distinguish between thirst and hunger. 

It’s recommended that women drink 2.7 litres of water per day, and men drink 3.7 litres, however, this will vary depending on lifestyle factors and the intensity or duration of your workout [6].

5. Get plenty of sleep

Sleep is imperative for muscle growth to occur, as it’s during this time that muscle tissue can repair and rebuild after a strenuous workout. It’s recommended that the average adult gets around 7-9 hours of sleep each night. 

According to a 2010 study, sleep impacts both muscle growth and fat loss [7].

After a trial group was split in two, with one having 8.5 hours of sleep per night and the other just 5.5 hours, it was found that despite both groups being on a calorie deficit and losing the same amount of weight, those getting less sleep lost 60% more muscle where the other group preserved it. 

So, while the saying “muscle weighs more than fat” is far from the truth, if you’re eating a balanced diet, exercising, and noticing changes to your body composition, like a leaner physique or losing inches from your midsection, it’s ok if such changes aren’t reflected on the scale.

Though setting a target goal weight can prove motivational, the number on the scale isn’t an indicator of your overall health or a measure of your success. 

Even so, we understand the power of seeing results when it comes to your weight loss journey and how an inability to budge the number on the scale can see you spiral.

That’s why, if you want to achieve long-term success, it’s worthwhile to consider Juniper’s Weight Reset Programme.

As well as providing breakthrough medication to help kickstart your journey, you’ll also receive hands-on support to stay on track with your goals in the form of certified UK clinicians and an online community who are ready to help you every step of the way. 

Whether you’re looking to change your body composition, gain muscle, or simply break those habits that keep holding you back from your goal weight, Juniper’s Weight Reset Programme can help you achieve your weight loss goals sooner and stick to them for the long term.

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