"Muscle weighs more than fat" has been used over and over and over by people; including extremely misinformed fitness enthusiasts. When I correct someone for using the phrase it often becomes an argument starting with "You're wrong!"
"How can you tell me that?" and, of course, "You're telling me everyone else is wrong?"
Since I'm going against the common misconception I must be wrong, and shouldn't be working in this field; or so the thought goes.
However, the fact is, muscle DOES NOT weigh more than fat. It is dense and compact, but it does not weigh more. Once more for good measure: Muscle does not weigh more than fat.
One pound of muscle = One pound of fat
16 oz. of muscle = 16 oz. of fat
453.59 grams of muscle = 453.59 grams of fat
The difference is volume- not weight. It's the amount of space that fat and muscle take up in the body that leads to this misconception. It is why fitness educators are consumed with body composition. It's also why so many of us loathe scales.
Read Weighing in: What does the scale offer?
The picture below is a great representation of the concept.