It’s obvious that 10 lbs. is 10 lbs., regardless of what it’s made up of. So, 10lbs. of fat weighs the same as 10lbs. of muscle. However, this doesn’t debunk the common statement that muscle weighs more than fat, as many people think it does.
Pound for pound, muscle tissue does take up less space than fat because muscle is more dense. And, since it is denser, muscle does weigh more than fat if you compare same-size portions. In that, density tells us how much matter is packed into a measured volume. So, the more dense an object is (i.e., the more particles in it are compressed together) the heavier it is compare to something of equal size with less particles.
The density of an object is often measured in grams per milliliter (g/ml). The density of skeletal muscle is 1.06 g/ml (1) whereas the density of adipose tissue (fat) is about 0.9 g/ml (2). Meaning 1 liter – a liter is a metric unit of volume – of muscle weighs 1.06 kg, or 2.3 lbs., compared to 1 liter of fat, which weighs .9 kg, or 1.98 lbs.
With the above in mind, the trouble with simply saying that “muscle weighs more than fat” comes from the fact that usually “weighs more” implies heavy and light, which, on their own, refer to mass, not density. Density is mass/volume whereas as weight is mass under the effect of gravity. The density of something stays the same wherever you take it, on Earth, Mars, or anywhere in the universe
The Bottom Line
The takeaway here is that the statement “muscle weighs more than fat” needs to be reworded to something like, “since muscle is more dense than fat, muscle does weigh more than fat if you compare same-size portions.” That’s not as sexy sounding, but it’s certainly more clear and accurate. Not to mention, you won’t have to keep hearing some one say “muscle doesn’t weigh more than fat because 1lb of muscle weighs the same as one 1lb of fat, you big dummy” in their best Fred Sanford voice.
- Melanie G. Urbancheka, et al. Specific Force Deficit in Skeletal Muscles of Old Rats Is Partially Explained by the Existence of Denervated Muscle Fibers. The Journals of Gerontology: Series A, Volume 56, Issue 5. Pp. B191-B197.
- M. S. Farvid, et al. Association of adiponectin and resistin with adipose tissue compartments, insulin resistance and dyslipidaemia. Diabetes, Obesity and Metabolism. Volume 7, Issue 4, pages 406–413, July 2005.
Nick’s Upcoming Live Events
Speaking at the NSCA Florida State Clinic in Miami, FL on September 26th, 2015.
Speaking at the NSCA Personal Trainers Conference in Anaheim, CA on October 10-12, 2015.
Teaching a private staff workshop at Impact Strength and Performance in Bellevue,WA on October 14th, 2015
Teaching a private staff workshop at Vigor Ground Fitness and Performance in Renton, WA on October 15th, 2015
Speaking at the VPS Elite Fitness and Performance Summit in Louisville, KY on October 16-17th, 2015.
Teaching a PreCon and Workshops at the NSCA Mid-Atlantic Regional Conference at Rowan University in Glassboro, New Jersey on December 4-5th, 2015.