A Dual-energy X-ray absorptiometry (DEXA or DXA) scan is the only accurate way of measuring body fat. Well, a DEXA scan is the only way to accurately measure body fat while you’re still alive. An autopsy is the other accurate way to measure body fat percentage.
How does a DEXA scan work?
Dual-energy X-ray absorptiometry (DXA, previously DEXA) is a means of measuring bone mineral density (BMD). Two X-ray beams with different energy levels are aimed at the patient’s bones. When soft tissue absorption is subtracted out, the BMD can be determined from the absorption of each beam by bone. Dual-energy X-ray absorptiometry is the most widely used and most thoroughly studied bone density measurement technology.
In real life, you lay down on a machine with your feet together and your arms by your side. You sit still for 10-15 minutes while a machine slowly moves from your head to your toe, centimeter by centimeter.
You can hear the machine “clicking” as the little ray goes back and forth across every inch of your body. You don’t feel anything. It doesn’t hurt or sting. You don’t need to wear any protective garments, as it’s not a dangerous scan.
What does a DEXA scan measure?
Everything. It measures your bone mass, your muscle mass, your fat mass, and your height.
(As you can see, my bones are dense from lifting weights and doing MMA/BJJ. Wolff’s law in action.)
It measures the weight of your head, your torso/truck, and each of your legs and arms.
A DXA scan will tell you how dense your bones are. In fact, DXA scans were originally designed and marketed to measure women for signs of osteoporosis, as woman’s bone mass decreases with age.
Being the original biohackers, bodybuilders quickly figured out that you can measure your body fat percentage accurately through a DEXA scan.
A note on the difference between visceral v subcutaneous fat.
A DEXA scan will tell you how much visceral fat you have. Visceral fat is the adipose tissue that surrounds your internal organs. It is the fat that kills you.
Subcutaneous fat is the fat that sits under your skin.
When you look at my scan, you’ll see that my body fat percentage is 19%. That may seem high by other standards, but DEXA scans generally give you a percentage of 3-5% higher than other measures of body fat, as it measures all of the fat.
People who get caught up in, “What’s my body fat %?” are shocked and upset when they get a DEXA scan done. They are shocked because other standards of measuring body fat underestimated body fat.
But body fat % is just a number for bros to compare on online message boards. What really matters if how you look, feel, and perform in and outside of the gym.
For example, I have “Fedor fat.” I look chubby even at a far lower body fat and I cannot get a six pack without my face completely sinking in. My 19% body fat hasn’t cost me any action, as I have the kind of body women want.
(This is what 19% body fat looks like. I’m 6′ and 206 pounds in this picture. P.S. That’s water, as I had just finished a contrast shower.)
That’s because, as you’ll see from my body fat % scan, I don’t hold any fat around my internal organs.
My waist is small and I wear a 31-33″ inch pants with no six pack. Meanwhile there are men with big waists who have abs. Those men tend to carry their body fat around their internal organs.
My aesthetic is cursed, but my lifelong health (check out my blood work) is good to go, as my body carries subcutaneous rather than visceral fat.
What does a DEXA scan look like?
A picture is worth a thousand words. As you can see in this image, a DEXA scan measures your body mass, your height, your tissue % in fat, your tissue % in muscle, and your bone mineral mass.
(This is what a DXA scan looks like.)
Pretty cool, isn’t it?
If you compare that DEXA scan to my previous DEXA scan, you can see how much muscle and fat I’ve gained over the past 5 years. The DEXA scan above is the “after” scan. Here is the before scan.
As you can see from those DEXA scans, this is what 20 pounds of muscle looks like.
How much does a DEXA scan cost?
That depends. Private labs charge between $60 and $100 for a DEXA scan.
Research universities often charge less. If you’re a student with some audacity, maybe you can get a scan done for free.
I paid $50 for my DEXA scan from UCLA and my DXA scan from a private lab cost me $60.
Is a DEXA scan safe?
A cross-country flight will expose you to more radiation than a DXA scan will.
So, yes, a DEXA scan is safe – safer than flying on an airplane.
How do you prepare for a DEXA scan?
There are no hard and fast rules, although its advised to not play with your hydration levels.
Don’t drink more (or less) water than usual. Skip your caffeine or other thermogenics on the morning of your exam. Don’t eat for 8-12 hours before your scan.
Wear loose fitting, comfortable clothing, as you’ll be laying down in a machine for 15 minutes.
You don’t feel the scan at all and it’s not dangerous.
Where can you get a DXA scan done?
Call the exercise physiology department of a nearby university. Most of the bigger colleges and universities have a DEXA machine.
Like I said, I had mine done at UCLA. It was only $50. If you live in Los Angeles, check out UCLA:
The Exercise and Metabolic Disease Research Laboratory is offering DXA Body Composition Analysis at a reduced rate in Los Angeles, California- only $50 per scan!
You can also call around to various doctor’s offices. Many of them use the scan to diagnose old ladies for osteoporosis, so it may take a minute or two for you to explain to them that you want your body fat % measured.
Any questions on DEXA scans?
Post them below!