Don't Take Body Fat Percentage Test Results Too Seriously I came across an interesting study today that underscores the point I always try to make whenever people start worrying about small changes in their body fat percentage (BF%). The study (Volume 22, Number 6, Page 1985 of The Journal of Strength and Conditioning Research) was concerned with evaluating a specific propriety body fat measurement device called the "Bod Pod", but to me the really interesting result was just how widely the BF% measurement results varied depending on the method of measurement. The same group of 30 female atheletes were professionally tested for BF% by four different methods and the results were all over the place: Hydrostatic Weighing (HW): 15.4% average, 4.8% standard dev.
Bod Pod: 19.3% average, 4.4% standard dev.
Skinfold: 17.7% average, 3.8% standard dev.
Dual-Energy X-Ray Absorptiometry (DEXA): 23.0% average, 5.8% standard dev. Somewhat ironically, of the four methods the two that disagree the most are the two that are considered "golden standards" of body composition measurement (HW and DEXA) -- one measured the group as having 15.4% body fat on average while the other as 23.0%! And remember, this is the same group of people undergoing professionally administered testing! What's the point of it all? The point is that body fat measurements are extremely unreliable, even in the best of circustances and that small or even not-so-small changes in measurement results do not necessarily mean much if anything about your body composition. To make matters worse most of the time the BF% measurements are not done by well trained professionals and, unfortunately, some gyms will purposely overstate your BF% in the beginning and understate it at the end of the training program to make it look like you made progress. You would do yourself a huge favor if you tracked your progress in either losing fat or gaining muscle NOT by measuring BF% but by measuring your weight (which is very reliable and easy to do) and by making sure that your weight very slowly but surely trends in the desired direction. If you are losing fat, 1 pound per week average loss is a good target pace for most people. And if you are gaining muscle, 2 pounds per month gained (about 1 pound for every two weeks) is also a good pace. And besides that the mirror and how tightly or loosely your clothes fit will tell the story as well. Any and all of these methods willl keep you on much better track than body fat measurements. | 
