Does Muscle Weigh More Than Fat? The Truth About Fat Vs. Muscle

How to lose weight and the best weight loss methods have to be among the most contested subjects these days. Between the obesity epidemic and the common desire to be thinner, almost everyone knows someone in their social circle who is thinking about how to lose weight or is actively trying to lose weight.

There are hundreds of fad diets, food products marketed as “lite” or conducive to specific diets; and all sorts of intense fitness challenges designed to support weight loss.

However, it also seems like there’s as much misinformation about weight loss circulating around as there is valuable, evidence-based recommendations and principles regarding how to lose weight.

Almost every time there’s a discussion or informal debate about weight loss between non-healthcare professionals, someone throws out the statement that muscle weighs more than fat.

But, does muscle weigh more than fat? If so, by how much? In this guide, we will look at fat vs. muscle and answer the increasingly popular question amongst runners and non-runners alike: “Does muscle weigh more than fat?”

We will look at: 

  • What Is Fat?
  • What Is Muscle?
  • Fat vs. Muscle
  • Does Muscle Weigh More Than Fat? And By How Much?
  • Fat vs. Muscle for Health

Let’s get started!

A person adjusting a scale.

What Is Fat?

Body fat, also called adipose tissue, is stored in the body to serve as energy reserves (fuel) for cells, insulation to help maintain body temperature, and protection or cushioning for organs.

Fat is stored under the skin (subcutaneous fat) and in your abdomen around your organs (visceral fat).

Subcutaneous fat is the more prevalent of the two, accounting for about 90% of your total body fat, according to Harvard Health Publishing. Visceral fat is believed to be more associated with potential adverse health conditions like insulin resistance, heart disease, metabolic syndrome, and type 2 diabetes.

Fat is stored in adipose cells as triglycerides, which can be oxidized for energy, particularly during low-intensity activity and rest.

Someone measuring their body fat.

What Is Muscle?

There are three primary types of muscles in the body—skeletal, cardiac, and smooth. Skeletal muscles are the muscles attached to bones and joints that enable movements, provide strength, and support posture and the skeleton at large. Cardiac muscle constitutes the heart and smooth muscles line the digestive tract and other organs.

Muscle tissue is primarily composed of protein, and is the only storage form of protein, or amino acids, in the body. Amino acids and proteins are involved in nearly every structure and function of the body in some way, from forming DNA to producing energy, to creating neurotransmitters to fueling white blood cells.

Alright, so let’s compare and really find out: does muscle weigh more than fat.

Fat vs. Muscle

Muscle tissue is more metabolically active than fat tissue, which is why your basal metabolic rate increases and you burn more calories even at rest when you gain muscle and lose fat.

What does this really mean? Your basal metabolic rate (BMR) refers to the calories your body burns at rest just to maintain your basic functions like breathing. 

The American Council on Exercise reports that your BMR represents about 60-75% of the total calories you burn in a day, with your physical activity and dietary-induced thermogenesis (calories burned digesting food) contributing the rest.

A person pointing at their watch which reads calories and steps.

Interestingly, while it is true that muscle burns more calories than fat at rest, this difference is not particularly significant. According to researchers, one pound of muscle burns about 6 calories at rest while a pound of fat burns 2 calories.

Therefore, if you gain five pounds of muscle and lose five pounds of fat, your total body weight will remain unchanged, but your basal metabolic rate will increase by 20 calories per day.

Let’s face it: 20 calories is not particularly significant. Since it takes a deficit of 3,500 calories to lose one pound of stored body fat, if you lost five pounds of fat and gained five pounds of muscle, it would take 175 days, or nearly six months to lose one pound.

However, before you feel defeated by this negligible difference, it’s important to keep in several things: the more muscle you gain, the more significant the metabolic boost will be and this only refers to increases as rest.

When you’re actually exercising, the metabolic rate of muscle increases precipitously, whereas fat continues to be minimally active. Therefore, the more muscle tissue you build, the more calories you’ll burn when you run or work out. 

Therefore, depending on the duration and intensity of your workouts, the total number of calories you burn in a day can actually increase substantially when your percentage of lean body mass increases and your body fat percentage decreases.

But, does muscle weigh more than fat?

A person flexing their bicep.

Does Muscle Weigh More Than Fat? And By How Much?

Now, on to the important question: Does muscle weigh more than fat?

The short answer is no, muscle does not weigh more than fat. 

One pound of muscle weighs the same as one pound of every other substance on Earth, whether that’s a pound of feathers, a pound of iron, a pound of flour, or a pound of fat. One pound is one pound of weight regardless as to the substance.

With that said, a pound of muscle and a pound of fat look quite different from a volume perspective just as a pound of feathers looks very different from a pound of sand.

Muscle is denser than fat, so one pound of muscle is more compact and takes up less room than one pound of fat.

Although it’s impossible to give a precise density of fat vs. muscle because these are live tissues that can vary in their exact nature, the average density of fat is about 0.9 g/mL, while the density of muscle is approximately 1.1 g/mL. 

A person measuring body fat, does fat weight more than muscle?

For reference, the density of room-temperature water is essentially 1.0 g/mL, so fat would float (because it is less dense than water) and muscle would sink (because it is more dense than water).

Using these metrics, it can be seen that fat is about 18% less dense than muscle tissue, or about 82% of the density of muscle.

Therefore, while one pound of fat weighs the same as one pound of muscle—and that is, by definition, one pound—a pound of muscle will be about 18% smaller than a pound of fat if the two tissues are sitting side by side on a scale.

This difference in volume is quite significant and is the reason why two people can weigh the same amount and be of the same height but can have very different builds. Someone with a higher body fat percentage will look fuller or larger whereas a more muscular person with less body fat will look slimmer. Muscle is denser than fat.

Similarly, if you start working out like our example who lost five pounds of body fat and gained five pounds of muscle, your clothing may be looser and you’ll look thinner even though the weight on the scale won’t change. 

In this case, the volume of your body has gone down because you’ve replaced denser muscle tissue with less dense fat tissue.

A tablet that reads body fat percentage, lemon slices and a tape measure.

Fat vs. Muscle for Health

Ultimately, one of the benefits of consistent exercise is that it can help shift your body composition to reduce your body fat percentage and increase your lean body mass.

As mentioned, muscle tissue is more metabolically active, so one one the benefits of increasing your muscle mass is that you’ll expend more calories. More importantly, excess body fat is associated with an increased risk of various diseases as well as all-cause mortality. 

How do you know if you have a healthy body composition? The ideal body fat percentage for runners is largely dependent on sex. The following are the typical body fat ranges given for men and women:

Men:

  • Essential Fat: < 5 percent
  • Athletes: 5 to 10 percent
  • General Fitness: 11 to 14 percent
  • Good Health: 15 to 20 percent
  • Overweight: 21 to 24 percent
  • Too High: > 24
People doing a kettlebell goblet squat.

Women:

  • Essential Fat: < 8 percent
  • Athletes: 8 to 15 percent
  • General Fitness: 16 to 23 percent
  • Good Health: 24 to 30 percent
  • Overweight: 31 to 36 percent
  • Too High: > 37

To gain muscle, aim for a minimum of 2-3 total-body strength training workouts per week using compound movements and progressive overload. For best results when it comes to hypertrophy (muscle growth), use a load you can handle for just 6-8 reps max.

To lose body fat, strive to create a moderate caloric deficit through a nutritious, calorie-controlled diet and/or consistent exercise. If you want to lose one pound of stored fat per week, this caloric deficit should be 500 calories per day.

Remember, when asking does muscle weight more than fat: a pound is a pound is a pound. A pound of fat weighs the same as a pound of muscle but it’s 122% the size of a pound of muscle.

Now that we’ve answered the all-popular question, does muscle weigh more than fat, perhaps you’ve decided to change some of your habits. If you are looking to better your nutrition, take a look at our information on healthy eating for runners:

The Best Popular Diets For Runners: 3 Healthy Choices

Running Nutrition Guide: What To Eat, For Runners

Ultramarathon Nutrition Guide

A plate of vegetables and hummus.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, and contributes to several fitness, health, and running websites and publications. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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