Age and Body Fat

Question:

How much does age affect body fat percentage? Using Omron's Body Fat testing device (the one where you hold the handles), I checked a client’s body fat at his age (45 years), and it came out at 22 percent. Then I retook it with all the same information except I made his age 35, and the BF dropped to 18 percent. I know that age is a part of all body fat formulas, but is it always such a big contributor?

Answer:

Body fat percentage has a very close relationship with age, a direct correlation as a matter of fact. As the body ages, the ability to synthesize and maintain lean tissue decreases due to hormonal changes and lifestyle factors. The measurement and percentage point changes sound about right in your statement. However, there is no concrete standard or percentage rate for body fat changes as you age. The calculations used with the various forms of technology that adjust for age are ballpark at best. This is partially due to the fact that there is a big difference between chronological age and biological age, as you can be much younger or older physiologically than you are chronologically.

I would like to put some perspective on your methods so you can have something to think about when acquiring body fat percentages. There are many forms of body fat testing. However, be careful with the technology you use to obtain body fat. The Omron handheld device uses electrical impedance technology, which has its flaws.

The Omron handheld uses bio-electrical impedance. The person stands on a scale or uses a handheld device and an electrical current is sent through the body. The calculation of body fat is then determined by how much resistance or impedance the flow of the current has going through your body. Fat happens to be a poor conductor of electricity, naturally being an insulator. Muscle or lean tissue is very hydrous and is a good conductor. Thus, the device can calculate how much body water is present. If you subtract that from total bodyweight, you get a body fat percentage. However, here are the flaws:

• The type of device you use can make a big difference, depending on the placement of the conductors (i.e., hands or feet). If you have a handheld, the device sends the current through one arm, across the chest and over to the other arm. If the feet are the conductors, the current is sent up one leg, into the abdominal wall and across to the other leg. People hold body fat in different places, which should be considered with the type of device you use. Women typically have most of their fat stores in the hips and thighs, so using a handheld device could give you a skewed percentage.
• The calculation of body fat percentage is totally contingent upon hydration level. Food, exercise, sleep and hormonal rhythms all affect hydration levels. These factors have to be considered in the margin of error.
• Another factor is the 24 hour period prior to taking the test. If you went out the night before and had alcohol (which dehydrates you), your body fat percentage will come out higher. If you drink a pint of water before you take the test, you can essentially come out with a lower body fat percentage. If you went out drinking the night before and wake up drinking a bunch of water because you’re so thirsty and your body is trying to deal with all of that, it’s anybody’s guess.

As you can see, using this technology without knowing your client and what he has been doing outside of the gym can make his day good or bad. My recommendation would be to use other forms of body fat testing to be compared against each other. Another suggestion would be to take multiple measurements throughout the day and average it out to get an idea of where your client stands. Electrical impedance is fast and easy, but the body is entirely too complex to manage all of the factors that affect hydration to come up with an accurate percentage. It would be like trying to catch a fish with your hand. Is it useless? Not at all, but I would take it with a grain of salt and remember that it’s just an estimate. Good luck.