I don’t use or recommend any of the body fat tests out there.
That’s mainly because they don’t tell me anything that I can’t see for myself by looking in the mirror.
If you really want some kind of “objective” way to measure how much fat you’re losing over time, I’d suggest using skinfold calipers. But just like body fat scales, they’re not without their problems.
Measuring body fat percentage with calipers involves pulling a fold of skin and fat away from the underlying muscle and measuring the thickness of that skinfold. Then you add up the numbers from several sites around the body and plug them into an equation, which then tells you what your body fat percentage is.
The first and probably most obvious source of error is that it’s quite normal for fat to be lost from certain parts of your body faster than it is from others.
This means that the reduction in skinfold thickness won’t be the same at various sites. You might be losing fat, just not from the places that are being measured.
There are several different regression equations used to estimate body fat percentage. which vary depending on your age, gender and ethnicity. But an equation is accurate only when it’s used to test people similar to the ones who were used to develop the equation in the first place.
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If you do use skinfolds calipers to estimate your body fat percentage, make sure to use an equation that was developed specifically for your race, age, and gender.
These equations also assume that the distribution of fat under the skin and internally is similar for everyone. Which it isn’t. And that your fat stores automatically increase the older you get. Which they don’t (just ask Clarence Bass).
As an example, let’s say that you have your body fat percentage measured the day before your birthday, and that the sum of your skinfold measurements is 30 millimeters. This might translate into a body fat percentage of 15%.
The next day, the sum of your skinfold measurements is still 30 millimeters. But because you’re now a year older, your body fat percentage will (according to the equation anyway) have gone up.
The best way to use skinfold thickness data is to use the raw numbers (i.e. the sum of skinfolds), which removes the error associated with using equations .
When you start your program, the sum of skinfolds might be 30 millimeters. After six weeks, this figure might have dropped to 25 millimeters. If the number is going down, you’re losing fat. If it’s going up, you’re gaining fat.
But even that method has its limitations.
Muscle growth can lead to the compression of the extracellular space between fat cells, creating the “illusion” of a reduction in skinfold thickness.
The total amount of fat under the skin (subcutaneous fat) remains the same. It just takes up less space because the muscle underneath it has got bigger.
In one study, training the arms for 12 weeks led to a decrease in subcutaneous fat when it was measured using a single skinfold measurement at the arms, but not when measured by MRI (which is able to detect changes along the entire upper arm) .
The skill of the person using the calipers is going to have a big impact on the results.
Your trainer should take several readings from each site, as well as leave a short break between each reading to avoid squeezing water out of the area. Very few take the time to do it properly.
Caliper technique can vary widely from person to person. The fact that most commercial gyms have such a high turnover rate of staff makes it very difficult to get skinfold measurements done by the same person each time.
Of all the methods available for measuring your body fat percentage, calipers are the best of a bad bunch. But I think you’re much better off relying on a combination of your weight on the scales, your strength levels in the gym and the way you look in the mirror.
As long as you’re honest with yourself about what you see, it’s as good a way as any for letting you know if your hard work is paying off.
1. Wells JC, Fewtrell MS. (2006). Measuring body composition. Archives of Disease in Children, 91, 612-617
2. Kostek MA, Pescatello LS, Seip RL, Angelopoulos TJ, Clarkson PM, Gordon PM, Moyna NM, Visich PS, Zoeller RF, Thompson PD, Hoffman EP, Price TB. (2007). Subcutaneous fat alterations resulting from an upper-body resistance training program. Medicine and Science in Sports and Exercise, 39, 1177-1185
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