In a world of misinformation, Fitness Pudding is here to separate fact from fallacy, and science from fiction.
“I’m not fat, I’m big boned.”
“I am overweight, because of my large bones.”
We might be quite familiar with such comments, but is there any truth to them?
First, take a moment and answer the following question. How many pounds do you think your skeleton weighs? 5 pounds? 10? 20? 40?
The DXA machine helped us to decipher if muscle actually weighs more than fat, and I think will help us answer the ‘big boned’ question.
The DXA estimates how much bone mineral we have in our entire skeleton, which we can convert to pounds.
Take these five, random scans of women I pulled from our lab’s DXA scanner. Their skeletons ranged from 4.9 to 6.2 pounds, which was only about 3 to 3.8% of their total body weight.
But are these women just outliers? Actually, no, they appear to be quite average, as compared to this large study of U.S. adults.1
These graphs are the bone mineral content for White, Black, and Mexican American women from 20 to 85 years of age. Each blue dot represents a person who was measured.
Their estimated skeleton weight averaged from about 3 to 4 pounds. In men, the average skeleton weight was about 5.5 to 6.5 pounds – with the heaviest skeletons being only about 11 pounds.
Personally, the largest skeleton I have scanned was a 350 pound professional football player, who had a 13 pound skeleton – still a mere 3.7% of his body weight.
In conclusion, this one is busted. We are not ‘big boned’, as the weight of our skeletons do not make a substantial contribution to our overall body weight.
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Kelly, T. L., Wilson, K. E., & Heymsfield, S. B. (2009). Dual energy X-Ray absorptiometry body composition reference values from NHANES. PLoS One, 4(9), e7038.
X-Ray Image: From Keith Martin documentary. http://www.channel5.com/show/70-stone-almost-dead.
Dr. Faries has a Ph.D. in Behavioral Medicine and a Master of Science in Exercise Physiology, balanced with experience across the fitness industry, medicine, public health, research and extension.
His research explores why and how people initiate and maintain healthy behaviors, with focus on self-regulation success and failure. In other words, he seeks to better understand the common struggle with adopting healthy lifestyles, clarifying the reasons why we don’t “just do it.” Dr. Faries also holds unique expertise in medication adherence, when lifestyle is the medicine.
Dr. Faries also trains the next generation of ‘myth busters’ through medical and public health education, including his popular course, MythBusters: Health Edition.
Dr. Faries has served on the Board of Directors of the American College of Lifestyle Medicine, is founder of Lone Star Lifestyle Medicine for Texas, and is founder of FitnessPudding.com – a non-profit site dedicated to debunking common health and fitness myths.