Muscle does not weigh more than fat.

Remember in secondary school (jr or sr high) science class learning about weight and mass? Whether on Earth or in space an object's mass is always the same, but its weight varies due to gravity?

Same applies here. There's a common misconception that "muscle weighs more than fat." Think about it -- 5 pounds of ice cream weighs the same as 5 pounds of lead. The difference, however, is the amount of ice cream it takes to make 5 pounds, and the size of lead it takes to make 5 pounds.

I found this picture to explain it a little better:




I think what people mean by "muscle weighs more than fat" is you can pack more muscle in the same space as you can fat, thus making the total amount of muscle in that space weigh more than the amount of fat in that space. Make sense? So tell your friends; muscle does not weigh more than fat. It's a law of science. :)