Dexa Scan Body Composition
DEXA stands for Dual-Energy X-ray Absorptiometry. It is a whole-body scan that uses two different types of low-dose X-ray beams to measure overall body composition with a special interest in body fat, Muscle Mass, and Bone Health. It is a simple, non-invasive, and painless procedure to accurately measure the amount of fat, muscle, and bone minerals in your body. Knowing your body composition can help you stay fit, healthy, and active and prevent diseases that can occur due to their derangements. For example, excess body fat, especially visceral fat, can predispose you to diseases like type 2 diabetes, hypertension, stroke, etc. Similarly, an extreme deficiency of fat can lead to cognitive dysfunctions and reproductive problems. Also, the deficiency in bone minerals can lead to weak bones and fractures.
Why and when do you need this test?
You may need to undergo this test for any of the following reasons;
- To establish your baseline measurements and follow an optimum diet plan and exercise to monitor your muscle growth and body fat loss.
- If you are an athlete, accurate body composition can allow you to improve it to obtain the maximum performance.
- To identify your long-term risks of diseases like metabolic syndrome, diabetes mellitus, and hypertension by calculating your visceral fat.
- To improve your bone health and prevent osteoporosis and fractures.
Do you need to prepare for the test?
DXA scan requires minimal preparation.
- Stay well hydrated and do not eat 3 hours before the scan.
- Do not take calcium supplements 24 hours before the test.
- Inform your doctor If you have recently had a contrast test (CT scan, MRI, etc.), as you may have to wait for 3-7 days for DXA in this case.
- You should not be wearing any metallic object, be it jewelry, a watch, or metallic zippers or buttons, as they can come in the way of X-rays and affect the results.
- Patients with prosthetic hip or metallic implants may need to inform their doctor.
- As the process uses X-rays, please inform your doctor if you are pregnant.
What can you expect?
- After entering the designated room, your weight and height will be measured.
- There will be a table for you to lie down above, which is a detector attached by an arm.
- The arm will move over your body several times to generate images on the attached computer.
- The scan will take 6-10 minutes
- You may need to lie down still to prevent the images from getting blurry
- You may return to your normal activities shortly after the test.
Are there any risks to this test?
It is an FDA-approved safe procedure that uses a very low radiation dose. However, it can harm a developing fetus, so it is unsafe for pregnant women.
What do the test results mean?
You will get a printout of some pages that will include the result in percentages. The results can tell you about the total body fat and regional fat, the fat present in each region of the body (arms, trunk, legs, pelvis, etc.). It can tell you about lean body muscle composition and bone density. It may include the values of the following parameters;
- Total Body Fat Percentage (%BF)
- Fat Mass Index (FMI)
- Visceral Adipose Tissue (VAT)
- Android to Gynoid Ratio/ apple to pear shape ratio
- Skeletal Muscle Mass (SMM)
- Appendicular Lean Mass to BMI Ratio (ALM/BMI)
- Bone Density
Simple tests to measure body composition may include anthropometric measurements like weight, height, skinfold measurements, and waist circumference. More complex methods include bioelectrical impedance, body density, and total body water estimates.
Advanced methods include,
- Computed X-ray tomography (CT),
- Magnetic resonance imaging (MRI)