Does Muscle Really Weigh More Than Fat?

It’s a claim that every athlete, dieter, or fitness enthusiast has heard over and over again: “muscle weighs more than fat.” If you’ve ever tried to lose weight through exercise, the chances are that you have used this claim to explain why, regardless of how many miles you run or bike in a week, the scale doesn’t seem to show considerable changes.

But is the claim that muscle weighs more than fat backed up with scientific fact? Or is it a misunderstood myth that gets oversimplified by the general public?

“A Pound is a pound”

If we’re honest, the latter answer is closer to being true. Indeed, many experts will label the “muscle weighs more than fat” statement as an outright myth. For instance, this article from Everyday Health quoted a professional fitness coordinator who debunked the concept with the simplest explanation possible: “a pound is a pound.” If you have five pounds apples and five pounds of steak, they both have identical weights. The same is true for muscle and fat. In other words, when you start to think critically about the statement “muscle weighs more than fat,” it doesn’t quite hold up.

does muscle weigh more than fat

Finding Truth in a Popular Myth

So if experts say that the “muscle weighs more than fat” argument is a myth, that means that it has no scientific validity, right?

Well, not quite.

It’s true that a pound is a pound, no matter the material or substance being weighed. However, it’s also true that, as you exercise more, you can feel and appear slimmer (e.g. shedding fat) but still weigh roughly the same when you step onto the scale.

How can these two facts exist simultaneously? Isn’t there a contradiction here somewhere?

The main problem with the “muscle weighs more than fat” myth is that it is focusing on the wrong measurement. Weight isn’t the relevant part of the conversation, because as we’ve already noted, a pound is a pound is a pound. The metric that exercisers should be looking at to explain why they look slimmer but weigh the same is density.

Muscle, Fat, and Density

Muscle is notably denser than fat. This statement, unlike “muscle weighs more than fat,” is the stuff of scientific fact. It’s also usually what people mean when they say that muscle weighs more than fat. Think about it this way: if you put a pound of human fat and a pound of human muscle on a balancing scale, the scale would be perfectly balanced.

The two loads would have the same weight: one pound. However, what the two loads would not have in common is volume. Since fat is denser than muscle, the “fat” side of the scale would look noticeably “fuller” than the muscle side of the scale. The muscle would take up less space than the fat, despite the fact that the two loads have the same weight.

fat vs muscle

5lbs of Fat vs 5lbs of Muscle. Source: OttawaMommyClub.ca

How much less space does muscle take up exactly? According to Livestrong, the average density of muscle figures out to about 1.1 grams per millilitre. By comparison, the average density of fat is 0.9 g/mL. A one-litre load of muscle, therefore, would weigh about 2.3 pounds, while a one-litre load of fat would only be 1.98 pounds.

On the body, this difference in weight can have a noticeable effect. Say for the sake of conversation that after three months of cardio workouts and strength training, you have lost five pounds of fat, but gained five pounds of muscle. The scale is still showing you the same weight, but when you look in the mirror, you look slimmer, leaner, and fitter.

Why Fitness Goals Based on Weight Only Can Be Misleading

This experience can be frustrating if you are exercising with weight loss as one of your primary goals. However, it also shows why measuring the effect of exercise based solely on weight is futile. If you lose five pounds of fat, then you have shed more than two and a half litres of volume from your body. If you gain five pounds of muscle, on the other hand, you would only add an extra 2.17 litres of volume to your body. There’s a difference in volume of 0.35 litres between the weight you lost in fat and the weight you gained in muscle. As a result, you will look and feel slimmer, even if you still weigh the same amount. The muscle you gained is taking up less space than the fat you lost.

How to Use This Information to Drive Your Fitness Regimen

The last big question is how you can use all of this information in your day-to-day life? Why is it so important to know that muscle doesn’t necessarily weigh more than fat and that density is the more important calculation?

Essentially, it’s necessary to banish the “muscle weighs more than fat” myth because of how it can skew a person’s perception of his or her fitness levels. Someone who is exercising frequently can write off any weight gains as “all muscle,” while another person can lose muscle mass, add a little extra fat, and still be “losing weight” according to the scale.

tape measure

Many experts will even encourage you to set the scale aside if you are starting an exercise regimen. With so many different types of diets earning “household name” status these days, it’s easy to place the focus of any fitness plan on losing weight. However, the better goal is to push for an improved muscle-fat ratio. When you are building muscle mass and trimming fat, you will start to slim down and to look better and feel better. If you judge only based on the scale, though, you might ignore these accomplishments—simply because you weigh more than you did when you started working out regularly.

The bottom line is this: losing fat is far more important than losing weight. The scale can’t differentiate between these two things, but the mirror can, and so can your sense of health and wellbeing. So toss out the “muscle weighs more than fat” myth, toss out the scale, and start using exercise first and foremost to make yourself feel healthier.

Trust us: you will be much more satisfied with the results.