Forums >Suggestions and Feature Requests>Body Fat
not bad for mile 25
Do these scales measure something besides weight to calculate body fat? The only ways I can think of would be either a caliper or an electrical conductivity test.
@LedLincoln
My (Tanita) scales use electrical conductivity/impedance. AIUI, that and weight - and details I set for height, age, gender (etc?) - are compared against a 'library of real people's details' to impute my Fat%
My scale (Tanita on athlete mode) has never been too far from underwater weighing when done the way it says to (hydration status etc). But I still wouldn't trust it because so much affects its accuracy.
My Tanita in athlete mode gave me a reading of 4% when I peaked for Boston this year, which I'm sure was far too generous.
Feeling the growl again
In shape mine is in the 5-7% range, which is reasonable....
"If you want to be a bad a$s, then do what a bad a$s does. There's your pep talk for today. Go Run." -- Slo_Hand
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Good Bad & The Monkey
How does knowing your body fat guide your day to day any more than just your weight?
I'm running somewhere tomorrow. It's going to be beautiful. I can't wait.
Poor baby
If your composition is not changing (ie lifting a lot of weights and adding muscle or something), probably not much.
One of many numbers we follow more on curiousity than anything.
As I rarely want to specifically lose/gain weight, knowing the weight of fat can be useful/ curious to me because...
My training load varies (for several sports), so a steady weight could hide muscle loss (or gain)
It wouldn't be a specific goal to exercise for weight loss, but if I think a trending weight gain is due to fat gain, it prompts me to consider my habits (eg. have I changed what/how much/how late I'm eating ...and do I need more sleep?)
Similarly, if I have a spike in weight gain, it can be useful to see that fat% moved as well (rather than thinking it's a glitch)
...But it's not a big deal. I have the data, and an easy way to chart it v's weight *may* improve the utility of the weight trend graph for me (..I don't know). That was all
SMART Approach
I have done hundreds ton of skin fold tests on people and have had them done on me by qualified/trained trainers. I have found that my Tanita scale is very accurate compared to skinfold testing when I use the scale late day. When I wake up in a.m. on empty stomach, partially dehydrated, the readings are higher. If I eat lunch and then normal fluid throughout the day but not within 2 hours of using the scale let say at 5pm before a run, my test is within 1% of the skin fold testing and about 3-4% lower that the morning reading. Having normal fluid intake, increases accuracy in my experience. I test it both ways/times just to monitor progress and water/fat weight. As mentioned, it is more like a toy for those of us into "numbers/stats".
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A bought my Tanita scale in 1999, when I started losing weight. I just wanted to be sure I was losing mostly fat. I was. I hadn't checked my body fat in years until last spring -- then I was just curious, as other people in the Boston group were reporting their body fat.
As Tchuck says, best to use it late in the day. Even so, it's a pretty noisy measurement -- like weight, but more so. You need to average over several days. Even then, it's changes in the average that are more relevant than the absolute number. At least, I never put much faith in the number as an accurate measurement.
If you measure it at the same point each day then the trend is likely to be indicative of something real; even if the absolute measurement is not that accurate.
Regular mode always has given me a much higher reading than underwater weighing though; goes to show much to trust it until you have done underwater weighing to compare its effects on you.