Does Muscle Weigh More Than Fat? It's Complicated.

FYI: The number on the scale isn't a health indicator.

Does fat weigh more than muscle, or does muscle weigh more than fat? While it seems to be common knowledge that muscle weighs more, that's not quite right. The answer depends more on the volume of each.

Consider the trick question: "What weighs more, a pound of feathers or a pound of bricks?" The answer, of course, is neither. A pound is a pound, regardless of the material. However, that pound of feathers will look bigger and fluffier than a compact pound of bricks.

So, while we're talking about the weight of muscle and fat, the root of the question is really body size and body composition. While it should be said, first and foremost, that body size or weight is not necessarily an indication of health, there is some truth behind the saying that muscle weighs more than fat.

You can be slimmer at a heavier weight than someone who's lighter, depending on how much non-fat mass (muscle, bones, and organs) you have in proportion to fat mass. Here's what you need to know.

Does Muscle Actually Weigh More Than Fat?

The short answer: Yes, muscle does weigh more than fat—by volume. The muscle will weigh more if you take a bowl of fat and compare it to a same-sized bowl of muscle.

That's the simple answer. But much more goes into that question, mainly how your body responds to these two tissues.

Muscle weighs more than fat because it's denser, said Joel Seedman, Ph.D., neuromuscular physiologist and owner of Advanced Human Performance in Suwanee, Ga. If you hold a fistful of muscle, it will weigh more than a fistful of fat because you technically have more of the compact tissue in your hand.

The catch: That number on the scale shouldn't matter here because the benefits of having more muscle tissue in the body outweigh having more fat tissue.

Getty Images - Animation: Alex Sandoval

How Having More Muscle Affects Your Health:

Muscle is a star player in keeping your body happy and healthy long-term for several reasons.

For starters, lean muscle mass can help manage blood sugar, keeping Type 2 diabetes at bay. A 2017 study published in PLoS One found a negative association between muscle mass and Type 2 diabetes—specifically, higher muscle mass meant a lower chance of developing the condition.

"The number one consumer of blood sugar in the human body is skeletal muscle," explained Tim Church, MD, MPH, Ph.D., professor of preventive medicine at Pennington Biomedical Research Center at Louisiana State University. So, the more muscle you have, the greater your potential to stabilize your blood sugar.

As a bonus, the blood sugar-regulating effect is instant and lasts after exercise. So if you do a workout today, your muscles will utilize blood sugar better over the next 72 hours, Church said.

Also, as you age, you'll want a healthy amount of muscle rather than fat.

"Muscle is a commonly overlooked marker of healthy aging," Church said. He added that you start losing muscle mass around age 40 or 45. This age-related decline in muscle is known as sarcopenia, one of the biggest reasons many older adults can have trouble doing simple tasks without help.

"You can't put your jacket on, push yourself off the toilet, and get yourself off the ground after you fall," Church said. "It all comes down to strength and muscle mass."

Even better news is that muscle can help you maintain a healthy weight by raising your basal metabolic rate or the number of calories you burn at rest. Exactly how many extra calories you'll burn by adding muscle is unclear.

"That number has been widely discussed and argued over the years," said Seedman. "But we know the more muscle you have, the faster your metabolism."

Lastly—and least importantly, at least in terms of health—the density of muscle might cause it to weigh more, which also means it takes up less space in the body. "If someone gains 10 pounds of muscle, a lot of times they'll barely notice that on their body," Seedman said, "whereas, if you gain five or 10 pounds of fat, you definitely notice that."

How Having Too Much Fat Affects You

While it's easy to see fat as an enemy, you need some body fat to survive (and even thrive). Fat tissue plays a few critical roles, from regulating body temperature and producing hormones to supporting brain health and insulating organs, said Church.

According to the American Council on Exercise (ACE), healthy body fat percentages for women range from 10%-31%. For men, it's 2%-24%.

When you go over that number, fat can potentially harm your health.

"People think fat is just excess energy storage, but it's really the number one driver of inflammatory markers in your blood," Church said. Chronic, or long-term, inflammation can contribute to various conditions, including Type 2 diabetes, arthritis, inflammatory bowel disease, and obesity.

A high body fat percentage has also been linked to heart problems. "There's a strong correlation between higher levels of body fat and an increased risk for cardiovascular disease and a number of other health issues," Seedman said.

How To Get Body Fat and Lean Muscle Mass Percentages:

There are a few cheap, easy ways to get an idea of your tissue percentages. Read on to find the best one for you.

Bioelectrical Impedance Scales

If you want to get a sense of how much body fat versus lean muscle mass you're carrying, consider a bioelectric impedance scale (also called a bioimpedance scale). Many devices that use this technology look like ordinary bathroom scales, but they measure your body composition through electrical impulses.

Don't worry, you can't feel it.

The downside is that bioelectric impedance scales can be hard to calibrate for accuracy, as any change in water weight (say, if you're dehydrated or have an illness) from one reading to the next may throw off the numbers. But, they can give you a good general idea.

Body Fat Calipers

Body fat calipers, also known as skinfold calipers, often look like big sets of tweezers. They're another inexpensive tool for measuring your body fat percentage. But Seedman suggested getting a fitness professional to take the reading because they'll have more practice getting accurate measurements.

You can also try a calculator on the ACE site if you have a pair.

Waist Circumference

Measuring your waist circumference may also help you keep tabs on body fat, as well as your risk for conditions like type 2 diabetes, high blood pressure, and heart disease, according to Church.

A waist measurement of more than 35 inches for non-pregnant women and 40 inches for men may show a higher risk of developing obesity-related health conditions. The Centers for Disease Control and Prevention (CDC) offers guidelines for taking accurate waist measurements. (Note, this doesn't exactly tell you your body fat percentage, but it will provide a glimpse into your health.)

Body Mass Index (BMI)

The most common way people measure body composition is through body mass index (or BMI).

While the CDC offers an online calculator for figuring it out, it doesn't consider your body fat percentage—a major pitfall to BMI numbers. So, if you've packed on muscle through resistance training, your BMI score may give you an inaccurate view of your health status.

There are also a lot of questions about whether it's a true measure of health, and whether it adequately represents racial and ethnic minorities.

How To Lose Fat and Gain Muscle in a Healthy Way:

Strength training is the smartest move for building muscle and cutting back on fat.

"If you only have a limited amount of time to work out, strength training is exponentially more powerful," Seedman said. He added that you could manipulate work and rest ratios to get more cardio benefits from your strength routine.

Seedman recommends doing a full-body strength routine at least twice a week. He also said to lift to the point of near-failure in each set—that means those last one or two reps should feel nearly impossible to do without breaking form.

If you're trying to shed fat while building muscle, keep the rest periods short between sets (30 to 60 seconds) to crank up the intensity of the sweat session. Choose five to six exercises (three lower-body, three upper-body) and shoot for 3-4 sets of 6-12 reps per move.

A Brief Overview

Muscle tissue weighs more than fat tissue if both take up the same amount of space. So, if you have a cup of muscle and one of fat, the muscle will weigh more. But don't let the prospect of weighing more keep you from building muscle, which will help you improve your health, reduce your risk of chronic disease, and age better.

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  1. American Council on Exercise. Tools and calculators.

  2. Centers for Disease Control and Prevention. Assessing your weight.

  3. Gutin I. In BMI we trust: reframing the body mass index as a measure of healthSoc Theory Health. 2018;16(3):256-271. doi: 10.1057/s41285-017-0055-0

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