T Nation

Bodyfat measurement confusion...

I’m trying to determine my BF%, and I’m getting conflicting results. Using a Tanita scale (which I know has HUGE variances based on time of day, hydration, etc), it typically measures at about 19%, in the early evening (7:30 PM). Using the Accumeasure plastic calipers, I get a about 14%, based on the Jason Norcross article and 7 site measurements.

One other anomoly, my front torso measurements (suprailic, midax, and chest) are all about 10 mm, which would translate to about 13% according to the chart that comes with the Accumeasure. About 7 years ago, I weighed almost 400 lbs, but for the last 4-5 years, I’ve been around 235-275. (I’m 6’2"). I’m wondering if the lack of elasticity in my skin has any affect on the caliper measurements. Based on pictures I’ve seen of other people who’ve stated their BF, I’d be more inclined to go with the Tanita measurements (19%).

Anyone have any experience in this area, or thoughts?

I don’t know what to tell you, other than you would be probably be better served using the Tanita first thing in the morning after relieving your bladder. The one constant you have at that time of day is the fact that you’ve been asleep and thus fasting for many hours. You’ll see a wider range in the evening (at least I do) since what you’ve done/eaten/drank during the day can have quite an impact. I know Tanita suggests you do it at night after a couple/few hours with no exercise, food, or drink, but aside from being able to ever find a time for me when that was the case, I still found the morning readings to be more consistent.

Also, how do you only measure 10mm on your torso measurements? That seems awfully low to me for someone your size and estimated body fat levels. So either you hold fat elsewhere, you’re not measuring correctly, or you’re overestimating your actual body fat levels. (Then again, perhaps I’m doing all of those things wrong).

Based on a fitness evaluation that I performed several weeks ago, I think that you’re right on the money in your thinking. The women in question had gone from 355 pounds to 165 in about two years. She had recently had a hydrostatic weighing test done at UNH. This measure placed her at 23%. I tested her with our digital skin calipers, only to find that due to excess skin, she was 38%.


Obviously, it’s tough to say without seeing a picture of you to get an idea of your skin condition, but I’d be willing to bet that the Tanita would be a better choice for you.

Tyler - yes, I think you’re right about taking the morning Tanita measurements. Typically, I’m about 24% BF in the morning. I would guess that this is a little higher than my actual BF%, but at least it’s a constant state/time.

Eric - thanks for the info. However, why do you think that the digital calipers are more accurate than the hydrostatic weighing? Would the excess skin count towards body fat?

I’d take HW over digital calipers (or anything, for that matter) anyday.

The main thing you need to understand, and what has also been proven in multiple scientific studies, is that the different measurement techniques DO NOT have good correlation. Of those available, the most accurate would probably be MRI body comp scanning, followed by Hydrostatic weighing. However these are complicated by the need for specialist equipment and technicians. I would say for your purposes both the Tanita, and the calipers are fine. Just choose the same time of day (sites of measurement) to try to get as accurate a re-testing as you can. No, you will not be 100% certain as to your exact BF, but there are extremely few circumstances I can think of when you NEED this accuracy. As long as you are making progress in your repeated measurements, and you are looking better in the MIRROR, what does increased accuracy give you??

(As a side note, the posts I see occasionally about people claiming BF measurements 6% and below are BS- most measuring techniques, MRI and HW included, become very unreliable at these low measurements, with a variation as much as 3-4%. I think this is due to the distortion created by the then disproportionately large essential fat stores in the brain, bone etc. on the overall score measured. At this level, it basically becomes a case of guessing, and saying -Yes, you’re pretty lean!)