I wasn't aware that there is a newer, supposedly more accurate technique for measuring body fat percentage. It's the DEXA scanner, which is used for measuring bone density.
I had a bone density scan today as part of an osteoporosis research study conducted by a local medical school. Along with my bone density results, they also gave me my total body fat percentage.
I didn't realize that the DEXA scanner could be used for this. I looked it up and apparently it's the new "gold standard" for body fat measurement:
www.new-fitness.com/body_fat_analyzing.html
DEXA (Dual Energy X-ray Absorptiometry) - A relatively new technology that is very accurate and precise, DEXA is based on a three-compartment model that divides the body into total body mineral, fat-free soft (lean) mass, and fat tissue mass. This technique is based on the assumption that bone mineral content is directly proportional to the amount of photon energy absorbed by the bone being studied.
DEXA uses a whole body scanner that has two low dose x-rays at different sources that read bone and soft tissue mass simultaneously. The sources are mounted beneath a table with a detector overhead. The scanner passes across a person's reclining body with data collected at 0.5 cm intervals. A scan takes between 10-20 minutes. It is safe and noninvasive with little burden to the individual, although a person must lie still throughout the procedure.
DEXA is fast becoming the new "gold standard" because it provides a higher degree of precision in only one measurement and has the ability to show exactly where fat is distributed throughout the body. It is very reliable and its results extremely repeatable; in addition, the method is safe and presents little burden to the subject. Although this method is not as accurate in measuring the extremely obese and the cost of equipment is high, DEXA is quickly moving from the laboratory setting into clinical studies.
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“I need you to lie down here,” Michelle says, indicating a sliding gurney beneath a movable QDR 4500 Hologic scanner arm. For the next three minutes, the arm glides back and forth, spraying my body with a piddling 5 microsieverts of radiation (the same amount we get each day just living on earth.)
The DEXA emits very little radiation. The comparisons that I found are that it is roughly equivalent to 20 minutes of sun exposure, or to the amount of radiation we absorb on an airline flight from New York to California.
The printout proves better than I could have hoped for. I’m down to 17.1 percent total body fat, which Hall says is distributed in a healthy, symmetrical way. My leanest parts are my legs—the left one at 14.2 percent fat, and the right one at 13.6. My abdomen, at 18.7 percent fat, is in no way suggestive of abdominal obesity, Hall says. To my surprise, my gut is not even my fattest body part. My head, at 20.1 percent, takes this dubious honor.
I found this part of the results amusing, too (as did the hubby). Who knew that our heads contained so much fat? We were wondering whether brain matter counts as fat or as "lean tissue". Here are my numbers:
Left arm ........ 23.6% fat
Right arm ....... 25.7% fat
Trunk ............ 14.9% fat
Left leg .......... 29.8% fat
Right leg ........ 31.3% fat
Head ............. 19.4% fat
Total body ...... 22.0% body fat
“I need you to lie down here,” Michelle says, indicating a sliding gurney beneath a movable QDR 4500 Hologic scanner arm. For the next three minutes, the arm glides back and forth, spraying my body with a piddling 5 microsieverts of radiation (the same amount we get each day just living on earth.)
The DEXA emits very little radiation. The comparisons that I found are that it is roughly equivalent to 20 minutes of sun exposure, or to the amount of radiation we absorb on an airline flight from New York to California.
The printout proves better than I could have hoped for. I’m down to 17.1 percent total body fat, which Hall says is distributed in a healthy, symmetrical way. My leanest parts are my legs—the left one at 14.2 percent fat, and the right one at 13.6. My abdomen, at 18.7 percent fat, is in no way suggestive of abdominal obesity, Hall says. To my surprise, my gut is not even my fattest body part. My head, at 20.1 percent, takes this dubious honor.
I found this part of the results amusing, too (as did the hubby). Who knew that our heads contained so much fat? We were wondering whether brain matter counts as fat or as "lean tissue". Here are my numbers:
Left arm ........ 23.6% fat
Right arm ....... 25.7% fat
Trunk ............ 14.9% fat
Left leg .......... 29.8% fat
Right leg ........ 31.3% fat
Head ............. 19.4% fat
Total body ...... 22.0% body fat
