New York Times bestselling author Tim Ferriss has written three 4-Hour books - the 4-Hour Workweek, the 4-Hour Chef, and the 4-Hour Body.  I have all three books, and am using the 4-Hour Body to help me change my body composition. I want a bit more muscle and a little less fat.  Ferriss provides some concrete steps to reach this goal.

One of the steps is to get your body fat measured.  A body fat measurement is expressed two ways. The first is as a percentage of total body mass. The second is the total amount of body fat you carry, expressed as a weight, usually in grams.

There are several ways to measure body fat, and each one gives different numbers.  You can use calipers, ultrasound, bio-electrical impedence - even an MRI or an X-ray CT scan.  I chose to go with a procedure called DEXA. DEXA stands for Dual Energy X-ray Absorptiometry.


DEXA Scan(125914)

DEXA, or DXA, measures more than body fat. It also measures bone density and lean muscle mass.  It works by sending two X-rays of different intensities through the body.  Bone, muscle and fat distribution is then calculated, based on the differences in absorption of the two rays.  The exposure to radiation is very low with DEXA machines, which is one of their advantages. 

The results contain all sorts of numbers and pictures. The numbers will tell you about your bone density and body composition.  They will tell you how much fat, bone and muscle you have, as well as their distribution on your body.   The pictures actually show where your bones, muscle and fat are. A colored picture shows a range of color from yellow through red to blue. Yellow represents fat, red represents muscle, and blue represents bone. A black and white picture will divide your body into zones. You can cross-reference the picture with a table indicating where on your body the muscle, fat and bone is found.  This is useful for weight loss because it can show where you carry sub-cutaneous fat  and the harder fat that surrounds internal organs.




DEXA scans are usually performed by a licensed technician, but that depends on local laws.  In North America they range in price, but you can probably expect to pay about $100 for a scan.  The technician will discuss the process and review the results with you. The scan itself takes 5 minutes or less, but the entire process takes between 45 minutes and 1 hour.

You are responsible for your own well-being.  Investing in your health is worthwhile.  Eating well and exercising are important, but data on your body is important.  The data is extremely important if you want to establish a benchmark for a body composition modification program. If you're considering making a change in your health a DEXA scan is a good place to start.