Does Muscle Weigh More than Fat? Let’s Investigate

‘Muscle weighs more than fat’ is a statement I guarantee we have all heard multiple times at different points on our fitness journeys.

You’ll usually hear it said if you have gained some weight after a period of training; a well-intentioned but misguided comment meant to make you feel better if the number on the scales has stayed the same or gone up.

The statement itself is pretty problematic — fat is necessary and essential for everyday human activity (including working out) — but aside from that, is the statement even true? 

Muscle vs. Fat: What is each one made of?

In answering the question of whether or not muscle does actually weigh more than fat, we need to consider what each one is and why they’re important.

Source: Photo courtesy of CrossFit Inc

Simply put, muscles allow us to move. They are necessary for force and motion, and are made up of bands of fibrous tissue which connect to your bones. For aesthetic and functional purposes, bigger muscles make us stronger and allow us to work harder, run faster, and burn more calories.

Fat, on the other hand, is where the body stores energy. Fat also protects your organs and helps the body absorb vital nutrients. There are also different types of fat found in food — saturated and and unsaturated — and to maintain a healthy diet, you want to limit the amount of saturated fat and replace it with unsaturated fats.

A certain level of fat is part of natural body composition. It’s made up of glycerol and fatty acids which aren’t as dense as the proteins that make up the tightly packed fibers found in your muscles.

And this is exactly why the statement ‘muscle weighs more than fat,’ is quite misleading; because weight has nothing to do with it.

So, does muscle weigh more than fat?

What does this tell us? Does muscle weigh more than fat? Well, the answer is no. A pound of fat and a pound of muscle essentially weigh the same, but the difference is in its density!

According to registered dietician and professor at the Baylor College of Medicine Roberta Anding, the way you look will be influenced by the type of tissue in your body. 

“Muscle is more compact than fat, so if you gain lean body mass, it is firm and occupies less space than fat” she says.

A good example Anding used was that a pound of marshmallows would take up more room than a pound of raisins, but they would still weigh the same. 

Source: CrossFit Inc

So this is where the statement comes from; seeing no change to the scales after weeks of training is thought of as a good thing if you’re strength training and fat loss isn’t your central goal. It means that you’re using up the body’s energy reserves and building lean muscle mass in tandem, essentially replacing one for the other. 

The phrase should really be ‘muscle is denser than fat,’ but that doesn’t have quite the same ring to it.

Does muscle weigh more than fat? Things to keep in mind

Our weight can fluctuate throughout the day, up to as much as 5 or 6 pounds, so every time you step on the scales, the number could be quite drastically different.

Here are other things that affect your weight on a day-to-day basis:

• Water retention
• Food intake / high-sodium foods
• Time of day
• Travelling long journeys
• PMS and different times on your cycle
• Sex, age, family history

All this tells us that our weight changes rapidly from first thing in the morning to late at night.

This means the scales probably aren’t your best indication of your fat loss vs. muscle gain; which can seem frustrating if you’re relying on that number for improvement. If you really want an accurate representation of your muscle mass you might want to look into different methods of measuring your fat to muscle ratio. 

One of the best ways of telling if you’ve gained muscle and lost fat is to look in the mirror! You know your own body better than anyone, and how you feel and what you see makes a bigger difference then the number on the scale.

What all this tells us is that fat isn’t quite the boogeyman the beauty industry likes to tell you it is. All bodies are built differently, meaning they retain and distribute fat differently; which is why someone’s weight is no real indication of how healthy or fit they are. However, if you stick to a calorie deficit with regular strength training, you will most likely achieve the results you desire.