Hey all - I’ve been keeping track of my body fat for some time now using digital calipers (measuring in 3 spots), and consistently have been gettin between 8 and 9%.
Yesterday, my company had a mobile hydrostatic water tank brought in and I had my body compisition taken. I figured it would be around 9%, or at most 1 or 2% more. Well, to my great surprise (and dismay), my bf registered at 16%! Then the little snot running the test starting giving me advice on how to change my diet to loose weight. (Yeah, I’m pissed). I plan to post a pic of myself, but just for some info, to me I don’t look to be 16%. From what I have seen with others, 16% shows a pretty noticable amount of body fat. I have no gut, and while my abs are a little covered by fat, they are still very visible. So am I deluding myself? Maybe I am really 16% and my caliper tests have just been way off.
Additionally, I don’t know if this matters, but I have increased my diet to 4000+ cals for the last several days prior to the hydrostatic test. Maybe extra food and water in my system made my bf appear higher than it is? Any thoughts would be appreciated.
I had mine done last April, both hydro and caliper ( not digital ) and this was done at the University of Wisconsin Sports and Medicine dept. Anyways, they gave me 8 different caliper readings varying from 3 spot to 7 spot tests and that ranged between 8-10%bf. The hydro put me at 15% bf… I know that I was much closer to the 15% rather then the 8-10%. I had some of my abs showing too, but there was alot of room for work though also. Only way to get different opinions would be to post a pick and let us critique…
Ditto Maximdiscord- unfortunately there are various sites of fat storage in the body. Some people carry more fat than others in muscle, some in viscera (organs such as liver, around the kidneys, heart), some in the bone itself. The ultimate storage area is the brain- it will cease to function if it gets below a certain F% (don’t ask me what this is, but it’s pretty high).
Hydrostatic does NOT differentiate between these different areas of storage. Calipers measure external fat storage only.
So my advice would be to go find a Tanita scale or similar, and get a measure on this. Then do the calipers again using multiple sites. If you could afford it of course, you could get a Dexxa scan (like an xray- showing full body composition).
Anyway, find the average of all the methods you use, and assume this to be your BF%. If the Hydrostatic appears way-out vs the others, it probably should be discounted. The bottom line is that all BF measurement systems have a large margin of error (save Dexa)
At the end of the day, as mentioned above, how do you LOOK?? If you can see abs, you’re DEFINATELY less than 16%, and probably closer to 10 or below.
Don’t let it get to you and train for how you look!SRS
i tested using the tanita bodyfat scale and it also gave me a higher results then i expected. The important thing is to use these measuring devices as a gauge. you just have to try to beat your previous number. People store body fat in different places. You might be able to see your abs but have no striations on your arms or legs. laters pk
Hey GTJason,
I too tried hydrostatic weighing about a year ago, cause I know that that is one of, if not THE best measurement for figuring out ones body fat. In any case, I had trouble exhaling all my air out of my lungs (residual volume??). For some damn reason, I just couldn’t grasp the concept of exhaling ALL my air our before I went under-water (rather than exhaling as I was going under water), I was told to hyperventalate and then just blow all my air out and then go under water. Well, because I couldn’t do this…I “floated” instead of sinking…which ended up giving me a higher % than I expected. Makes sense if you think about it…the more lean muscle a person has, the more they will sink! If you are a retard like me (haha), and cant exhale all the air out of your lungs, you will end up floating. Sooooo, needless to say, I didnt get the right reading. However, I do have a Tanita scale where I work and I am always in the 8-9% range.
Yeah, if you can see your abs, you’re well below 16%. The only exception to this would be if you were carrying a tremendous amount of lower body fat, but since you didn’t mention that, I assume you’re not. Just as with skinfolds, a hydrostatic test is only as good as the person running the test. It actually takes a lot of experience to run it correctly. Also, it takes a fair amount of instruction to get the person in the tank to do things correctly. So if this guy didn’t care too much, he may have let things slide too much. On a side note, the extra food you consumed probably didn’t make much difference unless it gave you a lot of gas. You can have your residual volume measured via the nitrogen washout test (did they do this?). But you cannot measure the amount of gas in your digestive tract, so it’s always assumed to be a certain amount based on your weight. Would it make an 8% difference if you had a ton of gas? Probably not. But it could have contributed to the error.
Did they measure or estimate your residual volume?
Did you definitely exhale all of the air in your lungs?
Do you get fairly gassy when you eat? GI gas will make you more buoyant and thus make it look like you have more fat.
In the end, there is no guarantee that the methods will be right in line with each other, nor is there a reason to really expect this. I suggest that you read my article right here at T-Mag to look deeper into actual body composition measurement. I’m more than happy to deal with any questions that arise also.
Hey thanks for all the info guys. I have always been a skinny bastard, but for the last year I have been eating more like a t-man. As long as my bf was under 10% I was happy. It was a shock to my ego to go in and have the unathletic guy running the test tell me I’m 16% just like him. Then he starts giving me diet and training advice.
Tony - yes I might not have blown all the air out. Regardless, the guy running the test wasn’t paying a lot of attention to what I was doing. That bugged me straight off since I was paying $40 for it.
dcb - no I don’t have much body fat on my lower body. In fact the fat I do have (by appearance at least), is on my lower abdonmin. Again, I can’t stick my gut out, but there is some flab covering my abs. No, I didn’t have the nitrogen washout test done.
Again guys, thanks for the info and ego boost. I’ll post a pic hopefully within the next week (I was planning to anyways). Also, I plan on getting my bf measured by calipers by someone else other than me (at the gym or health center at work). Later all
I offer the following from Dan Duchaine (BODYOPUS):
“[hydrostatic weighing] is not very accurate below 15 percent body fat.”
“…hydrostatic weighing doesn’t measure black people very accurately, because the density assumptions are wrong.”
“All electronic devices assume that 73 percent of lean body weight is water, which is not always true.”
Dan goes on to say (and I agree 100%) that calipers (when used correctly) are the single most accurate means of measuring body fat - especially for lean individuals.
As for interorgan fat, Dan coins “3 percent of your body weight” as being a solid assumption for those who aren’t obese. In other words, the most accurate percentage that you’re going to get is to take your caliper measurements and add 3% to them.
(Of course, nobody would ever really want to get rid of that interorgan fat, so I can see the rational for ignoring it alltogether…)
Colonel: That’s a good call brah. I do my caliper readings (three site) and they are always hyper low, but adding that 3% would make the readings turn out about right. It’s all coming into place.
Like J-Cross said, the first thing that needs to be known is whether you estimated or directly measured residual volume.
If it was just an estimate and it was an overestimate, then it would underestimate your bodyfat. If it was an underestimate, then the opposite is true.
The same holds true for your exhalation under water. If you didn’t exhale all your air, then it’s probably an overestimate. This would decrease body density.
Another factor would be the calibration of the weighing device.
All that said, hydrostatic weighing is a much, much more accurate method of body comp assessment than skinfold calipers.
It was the gold-standard…until DXA (i.e. dual-energy x-ray absorptiometry) showed up.
Hydrostatic weighing has an error of +/-2%, while DXA is more along the lines of +/-1%, with no source of outside error.
Tanita scales and bioelectrical impedence, in general, can be considered reliable…that is, consistently inaccurate. They are not a good assessment for accuracy for athletic populations.
Skinfolds should be used more for monitoring skinfold thicknesses (individually) and for relative changes, rather than absolute percentages.
How long did you fast before your test??? I was offered a free body comp test for a kines experiment at my university. I’m thinking “Great, I can get an accurate readyin of my bf.” Then i get an email saying i have to fast for TWELVE hours before the test. On top of that the test takes 3-4 hours. HOW THE HELL IS A T-MAN NOT SUPPOSED TO EAT FOR 16 HOURS?!?!?!