The classic brain teaser asks, “What weighs more, a ton of bricks or a ton of feathers?” Unfazed by this childish trickery, we would answer that they would weight the same – one ton.
Using the same rationale, could we answer, “Does muscle weigh more than fat?” And this is our question for the day.
Pound versus pound, sure, they would be the same. One pound of muscle weighs the same as one pound of fat.
On the other hand, if you took a square inch of muscle, it would weigh more than a square inch of fat, just like a square foot of bricks would weigh more than a square foot of feather.
This is why my Wii character says I am overweight.
But, this question is commonly aroused when someone steps on the scale, and attempts to determine where the weight is coming from. We might hear, “I weigh this much, because I have a lot of muscle, and muscle weighs more than fat.”
I think we can decipher this brain teaser with a basic understanding of body composition.
Body Composition
Our bodies are composed of many things, including muscle, skin, organs, fat, and bones. Usually, our body composition is broken down as follows:
- Fat Tissue,
- Lean Tissue, mainly muscle, and
- Bone.
Each of these contribute a percentage to your total body weight. They will add up to 100%. For example, what percentage of your body do you think is just fat tissue? 10%? 30%? 60%?
We have big fancy machines that can measure each of these for us. The ‘gold-standard’ is with dual-energy x-ray machines, or DXA, for short. We have one in our lab, so I pulled some random, anonymous scans to illustrate.
This is what a scan looks like [see video]. You see it provides an image of the skeleton, and what we call the ‘soft tissue’, which is everything but the skeleton. All this data over here shows how much muscle, fat and bone she has, not only her total body, but for her arms, legs, and trunk.
This particular woman weighs 163.5 pounds. 92.1 pounds of her weight is from lean tissue, which again, is mostly muscle. 66.5 pounds of her weight is fat, which is 40.6% of her total body.
Although there is no nationally recognized standard, women are commonly recommended be around 33% or under for health risks.
For this particular woman, we would recommend that she lose body fat, but not muscle or bone.
Fat is the health concern, especially the fat inside around her organs, which is called visceral fat.
For example, take woman #2 who also weighs 163.5 pounds. However, only 33% of her body weight is fat, which equates to 54.5 pounds. She also has 104 pounds of lean tissue. At the same body weight, she has 12 more pounds of lean mass, and 12 less pounds of fat than woman #1.
Also, notice that she her body fat percentage is not too high, as it is just at the 33% mark.
Conclusion
So, to our original question.
One person could weigh more than the next person, because they have more muscle, but also because they have more fat. This is an issue of body composition.
Stay tuned for the next post using the DXA scans to decode the myth that we weigh more, because we are ‘big boned’.