Your Body Recomposition Efforts May Be Missing This Piece Of Data, MD Explains
Having body recomposition goals is one thing, but understanding your baseline and tracking progress over time will show you what your efforts are really contributing to. One underutilized test can help you get a better picture on your body composition and where excess fat may be hiding.
What is a DEXA (or DXA) scan?
A DEXA scan (sometimes also spelled DXA) is a test that uses low amounts of radiation (as much as a dental X-Ray) to understand body composition. Commonly used to determine bone density while screening patients for osteoporosis and osteopenia, the same technology can be used to assess an individual’s lean mass (muscle, organs) and fat mass, at the same time as bone mass. The technology is safe and accurate, estimating body fat within 2-3% of more expensive tools used to measure body fat such as CT scans (which can have high amounts of radiation) or MRI (which can take 30 minutes or more).
Why get a DEXA Scan performed?
A DEXAis significantly more accurate1 than even the most accurate scale that offers body composition and offers precision measurements of muscle mass in different areas of your body, as well as measurements of the different kinds of fat in your body:
Subcutaneous Fat: the fat you generally think of and can feel on your body, this kind of fat sits just under your skin and can be found all throughout the body. It accounts for approximately 80% of your body fat. While it produces some hormones, its purpose is cushioning, heat production, and energy storage.
Visceral Fat: this is the more worrisome form of fat that is packed deep inside of organs and wraps around your guts. It can make a belly stick out and feel firm; it can also exist in high quantities even when BMI is normal. This is the fat that has greater impacts on your health. It functions as an endocrine gland and higher proportions of visceral fat2 is associated with insulin resistance, metabolic syndrome, and the conditions that come along with it such as type 2 diabetes, hypertension, high cholesterol, and heart disease. Certain medical conditions—Cushing syndrome, acromegaly, insulin resistance, perimenopause and the menopause transition—all of these conditions lead to an increase in visceral fat and this leads to small increases in inflammation throughout the body.
It can also be used to measure bone density, although most commercial DEXA scans provide less data about bones than the one you get as part of osteoporosis screening (which most people don’t realize is a different protocol), and can give you an idea of how your bone mass compares to others.
Muscle mass measurements are compartmentalized, meaning you can see how much muscle mass you have in each arm, leg, etc. This data can subsequently be used to show areas needed for improvement versus areas that need more work.
It also calculates Lean Mass to Height Ratio, which is an estimate of lean mass (muscle mass and bone mass) as a ratio to your overall height. Low ratios of this value can indicate low muscle mass, which is a risk factor for other health conditions.
What a DEXA Scan won't do for you
It won’t replace the bone density measurements that your doctor may want to get to ensure that you don’t have osteoporosis. The machine used for both is the same, but the protocol used, as well as the images taken, are slightly different. That means the data from a DEXA scan used to screen for osteoporosis will show slightly different results than what you get from a DEXA performed for body composition.
A DEXA won’t magically lead to weight loss, the work still needs to be put in of course, but this data can be brought to your doctor, your trainer, or your nutritionist to help you understand what your deficiencies are, and may even point towards the need for other tests or evaluation.
More FAQs about DEXA scans
Who should get a DEXA scan?
Really anyone at all would benefit from having more information about their distribution of fat, muscle and bone throughout their body, but this test can be particularly useful for:
- Those about to start a weight loss medication
- Those about to start a weight training or exercise program to monitor for progress
- Those about to start on a diet
What happens during a DXA scan?
- Your DEXA technologist will ask you to remove any jewelry and confirm you are not pregnant (radiation at any level is generally avoided for developing fetuses)
- Your height and weight will be measured with conventional tools
- You will lie on your back on a flat, padded, open table (no tunnel like in a MRI or CT Scan, OK for patients with claustrophobia)
- A scanner will pass overhead over the course of 5-10 minutes
- Results are read by a radiology team.
Are these covered by insurance?
Unfortunately, very rarely, if at all, do insurance companies cover this test.
How much do they cost? Do they require a prescription?
The tests cost anywhere from $50-300, depending on where in the country you get them done. You do not need a prescription. Several reliable testing companies have emerged Bodyspec and Dexafit, among others) which have locations nationwide.
The takeaway
A DEXA can be a valuable tool if you’re focused on body recomposition, by helping you understand your lean muscle mass versus fat, and how it’s distributed throughout the body. That being said, it’s not doing any of the actual work for you—you still need to think about your diet, exercise, and other lifestyle habits in order to make a true, lasting change.