You Ask, I Answer: Muscle vs. Fat

Could you please clear up the “muscle weighs more than fat” myth?

It always bugs me when I hear this because a pound of muscle and a pound of fat both weigh a pound.

Muscle is simply denser than fat—correct?

-- Anonymous
Via the blog

Yes, let's put this one to rest.

You are absolutely correct; a pound of muscle weighs just as much as a pound of fat (after all, a pound is a pound is a pound).

What people really mean to say is precisely what you're asking me to confirm -- muscle is simply more dense than fat.

In essence, a pound of muscle takes up less space than a pound of fat.

Let's use a suitcase analogy. A two pound dumbbell takes up less space than two pounds' worth of ping-pong balls.

The same thing occurs with fat and muscle.

This is why the scale often does not budge when someone starts a fitness program that implements weight training.

Fat is lost, muscle is gained, and although body composition changes (and your jeans are less snug), weight does not alter much.