Body Fat Measurement: The Facts on Why, How and How Much

If you're exercising regularly, chances are that your body composition is changing. Muscle weighs more than fat, so your body fat can be dropping and you won't see a change on the scale. One thing that could be happening is that you are losing bodyfat and replacing it with muscle. How then can you know if this is happening to you? And if you lose weight, how do you know if you're losing the fat you want to lose, or muscle tone instead?

Body Fat Measurement - Not Just For Athletes Anymore!
A body fat measurement is the best way to track your lean muscle mass versus fat mass over time. Even very slim people can have dangerously high body fat levels, which are correlated to certain health risks. Having too little body fat can be dangerous as well (although most of us will never run that risk!).

There are several ways of measuring body fat. These include hydrostatic weighing, calipers, and bioelectrical impedance. Hydrostatic Weighing is considered the "gold standard" of bodyfat measurement. This is where you get submerged in a tank of water, expelling all the oxygen from your lungs. Unfortunately, it's very expensive - about $200 or more per "dunking" from what I've seen.

Some gyms offer bodyfat measurements for free or a nominal fee by their personal trainers; unfortunately, these are almost always done with calipers. Calipers are small plastic devices that are actually clipped to your side (and arm, and thigh) to measure the thickness of the fatfolds there. The accuracy of this type of measurement is also dependent upon the quality of the calipers and the skill of the technician. These skinfold measurements are then compared to a chart that calculates your bodyfat based upon your age. Unfortunately, there is no accounting for your height, weight or bone structure in these charts. So the same percentage would be given to a 5'2" small boned woman weighing 100 pounds as to a 5'9' large boned woman weighing 155, as long as they were both the same age. Maybe it's just me, but the logic behind using a fixed number to calculate a percentage of bodyfat, without taking the other factors into account just doesn't make sense to me.

There are also some new devices on the market that measure your bodyfat in the privacy of your own home using Bioelectrical Impedance Analysis (BIA). BIA is a measurement of the electrical resistance in your body. A tiny electrical current is passed through your body, either from hand to hand or foot to foot. These units measure the resistance they encounter, and calculate that into how much of your body mass is fat versus muscle. They use your height, weight and exercise frequency to calculate your bodyfat. These used to cost up to $300; however, you can now get a personal BIA bodyfat analyzer for under $50! Let's look at two different types of bioelectrical impedance bodyfat analyzers specifically.

Bioimpedance Analyzers:
Two examples of bioimpedance bodyfat analyzers are the Tanita Bodyfat monitor/scale and the Omron Body Logic Body Fat Analyzer. These both use bioelectrical resistance to calculate bodyfat, but are slightly different devices. If you're interested in tracking your bodyfat, you might want to consider one of these devices. Let's look at how these two work specifically.

The Tanita Bodyfat Monitor/Scale looks like a regular scale, somewhat. It sits on the floor, and has a little digital readout at the top. There are two small metal plates on each side, though, for your feet. You first program in your age, height, and athletic background (whether you workout 4 times a week or more) and set that. You only have to do this once, then the unit stores it. You then stand on the scale in your bare feet, and it gives you your accurate weight as well as a percentage of bodyfat. This takes about 8-10 seconds total, and is extremely accurate.

Tanita sells scales that are for one, two or four users; for adults only or for adults/teens; and for everyday users or everyday/athletes. The list prices on these $74.99 - $254.99; however, I have seen these on sale online for as low as $59.95!

The Omron Body Logic Analyzer differs from the Tanita scale in several significant ways. It still uses bioelectrical impedance to measure bodyfat; however, it does so through the hands not the feet. This is a smaller device, about the size of a video cassette case, that you hold in your hands. You enter your personal information (height, age, athlete level - if appropriate - and age) into the unit. It can store up to four users in the memory, so you only have to program it once. Then you hit start and in seconds the analyzer tells you your bodyfat in both percentage and pounds.

There are two models of the Body Logic device. The HBF 300BL is the "Pro" version and has a keypad to enter your data with. This is the more expensive model, probably more appropriate for high volume users who need to enter a lot of different people's data quickly (like schools or personal trainers, etc). The HBF 301BL is the home user model, where you have to scroll through the options to enter your data but you can still store it in the memory, and this sells for far less (retails for $99 but it's on sale at Servicemerchandise.com for under $33. With either unit you have to enter your weight into the equation, which makes it good for people who already have a scale or aren't trying to lose weight, just body fat.

So What's Right for Me?
When you look at a body fat scale, you have to decide if you really are concerned about your bodyfat, or just your weight. If you are exercising and want to feel like you are accomplishing something (even when you hit those plateaus) and/or you are concerned about your overall health and want to focus on more than just your pure weight, bodyfat measurement can be a useful tool for you. For example, if you lose four pounds, don't you want to know that you lost four pounds of fat, not of muscle?

If you already have a good scale, especially if your weight is not changing (or not changing rapidly) the Omron device may work well for you. It's handheld, a little less expensive, and tells you your bodyfat in both pounds and percentage. It's also small enough to tuck in your gym bag or backpack, and you don't have to have bare feet to use it.

If you are trying to lose weight and like a very accurate scale, the Tanita body fat monitor/scale may be a better match for you. You do need bare feet to use it; however, it gives you your weight and body fat percentage in only a few seconds. It sits on your floor like a regular scale, and can be used as a regular scale (no bodyfat measurement) if you prefer.

Some tips for bodyfat measurement:

• Always try to measure your bodyfat at the same time of day (once a week should be sufficient to monitor changes)
  
• Try to measure your bodyfat when you have not had anything to eat or drink within two hours, especially no alcohol or caffeine
  
• Try not to measure your bodyfat immediately after exercising, as you will probably be dehydrated and get a less accurate measurement
  
• Measure with an empty bladder
  
• First thing in the morning you are usually not well hydrated, so this is not the best time to measure
  
• Be sure to research your body fat scale well, to choose the right one for you, and shop around online using a search engine for a good price before buying!