# hydration & body fat scale readings



## dirkfh (Jan 20, 2004)

How does hydration affect the output on a body fat scale? When is the most accurate time of day to check your body fat? I have been told the best time is the first thing in the morning before any food intake. Is this true?
I have noticed that if I have a few beers, the next morning my body fat reading is higher than I suspect it should be. Also, I just returned from mexico with a slight bid of Monetzuma's revenge. This has dehydrated me quit a bit. My body fat has shot up approx 2%. 

Thanks for input.

DFH


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## MTBXC (Jun 2, 2004)

*First thing in the am!*

The user guide on my electronic BF scale says that in order to get the most accurate readings is in the morning right after waking and right after the first pee. It also states that in order to get a more accurate reading that you must do this for several days in a row and then get an average reading. This is supposed to eliminate the dehydration factor.

I've been using mine for about 2 years and I also went to my gym and paid to have a professional trainer/nutritionist take a reading where they use electronic calipers and measure several different places on your body. there was a 1% diffrence in my scale and the professionals calipers. My scale said my BF was 9% and the other said it was 10%. Of course I like my reading better!


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## dirkfh (Jan 20, 2004)

*Thanks for the input*

Thanks for the help. Ten % body fat? Your in much bettter shape than me. Again thanks for the help.

Dirk


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## LBmtb (Jul 29, 2004)

dirkfh said:


> Thanks for the help. Ten % body fat? Your in much bettter shape than me. Again thanks for the help.
> 
> Dirk


 He's at my goal %age. I'm currently hovering around 13% and wanna get down to 10 . . .


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## bike4miles (Nov 14, 2004)

dirkfh said:


> How does hydration affect the output on a body fat scale? When is the most accurate time of day to check your body fat? I have been told the best time is the first thing in the morning before any food intake. Is this true?
> 
> Thanks for input.
> 
> DFH


I have found that I have very poor hydration in the morning and I end up seeing nubers in the mid teens like 12 to 14%. That is way too high for me. Later in the middle of the day after I am hydrated it will be back down to abour 6 to 8% which is much closer to what I beleve it should be for me. Try difernt times of the day and watch the fluctuations. I beleve hydration is the key factor.


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## millennium (Jan 13, 2004)

Hydration affects the reading of these scales because the electrical signal will pass slower or faster through a fat-free tissue depending on the concentration of electrolytes in that tissue--concentration of electrolytes goes up in dehydrated tissue.

Upon first waking in the morning, you are not well hydrated, so do not trust early morning readings. Try your scale during different times of the day. For me, I get readings that seem to be the most accurate/consistent in the late afternoon (before dinner--as long as I have peed before getting on the scale). Also, it has been shown in testing that these scales are not reliable indicators of small changes in fat percentage from day to day (probably because of the hydration issue)--so look for multi-day trends, rather than day-to-day fluctuations.



dirkfh said:


> How does hydration affect the output on a body fat scale? When is the most accurate time of day to check your body fat? I have been told the best time is the first thing in the morning before any food intake. Is this true?
> I have noticed that if I have a few beers, the next morning my body fat reading is higher than I suspect it should be. Also, I just returned from mexico with a slight bid of Monetzuma's revenge. This has dehydrated me quit a bit. My body fat has shot up approx 2%.
> 
> Thanks for input.
> ...


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## BelaySlave (Aug 4, 2004)

I've had my body fat scale for over a year. I usually check my weight and body fat % at night. I have had two body fat tests done at my gym at night and those tests came to within 1-2% of what I get from my body fat scale. So to stay consistent I just do my readings at night.


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## TrailRiddler (Feb 23, 2004)

Along the lines of hydration... watch your caffine intake before measurements. The tanita manual has a blurb about this.


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## bikerx40 (Jan 9, 2004)

I thought that my Tanita scale's user manual stated that the most consistent time to measure body fat % was around 7-8pm. Sure enough, I find that my weight is most consistent in the morning, while my body fat % is most consistent in the evening. I can't remember their logic about this though...


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## litespeedblur (Nov 13, 2004)

*Scale recommendation?*

Are any of the scales more reliable than others. Does it make a difference what brand I buy?


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## lot8con8 (Jul 5, 2004)

litespeedblur said:


> Are any of the scales more reliable than others. Does it make a difference what brand I buy?


Maybe an odd question; but how do you find out what your optimum body fat % is for your age? Or is there no real optimum point?

Thanks.

JG


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## rapwithtom (Feb 26, 2004)

*Tanita + My Anal Retentiveness*

OK I am hesitant to post this because I fear you all will realize that I have way too much time on my hands, but here goes anyway:

I got my Tanita scale last spring and noticed some of the variability issues you all are discussing. To get my hands around it, one I woke up one morning and weighed myself a bunch of times...see the below table.

What I learned:
- Repeatability & consistency are excellent
- Precision is very good (ie appropriate increase in weight after a drink of water)
- Bodyfat %age not impacted by how much water is in my esophogus/stomach/bladder
- Bodyfat %age is impacted by something related to body temperature/activity level, hence you will get different readings if you measure when you immediately wake up than if you measure later in the day. Also, since I know my actual bodyfat, I can say that the morning measurements were overstated while measurements in the afternoon were accurate.

Cheers
Tom

Date	Weight	Body Fat	LBM	FBM

Immediate after Wakeup
5/20/2004	195.8 17.1%	162.3 33.5 
5/20/2004	195.8 17.0%	162.5 33.3 
5/20/2004	196.4 17.3%	162.4 34.0 
5/20/2004	196.2 17.1%	162.6 33.6 
5/20/2004	196.2 17.0%	162.8 33.4 
Average	196.1 17.1%	162.6 33.5

wakeup + 12 oz water
5/20/2004	197.4 17.3%	163.2 34.2 
5/20/2004	197.6 17.2%	163.6 34.0 
5/20/2004	197.4 17.2%	163.4 34.0 
5/20/2004	197.4 17.2%	163.4 34.0 
5/20/2004	197.2 17.1%	163.5 33.7 
Average	197.4 17.2%	163.4 34.0

wakeup + 24 oz water
5/20/2004	197.8 17.3%	163.6 34.2 
5/20/2004	197.2 17.0%	163.7 33.5 
5/20/2004	197.4 17.0%	163.8 33.6 
5/20/2004	197.4 16.9%	164.0 33.4 
5/20/2004	197.4 16.4%	165.0 32.4 
Average	197.4 16.9%	164.0 33.4

wakeup + 24 oz water + shower
5/20/2004	196.8 14.7%	167.9 28.9 
5/20/2004	196.8 14.7%	167.9 28.9 
5/20/2004	197.0 14.8%	167.8 29.2 
5/20/2004	197.0 14.8%	167.8 29.2 
5/20/2004	197.2 14.8%	168.0 29.2 
Average	197.0 14.8% 167.9 29.1

wakeup + 24 oz water + shower + pee
5/20/2004	196.6 14.7%	167.7 28.9 
5/20/2004	196.6 14.7%	167.7 28.9 
5/20/2004	197.0 14.7%	168.0 29.0 
5/20/2004	196.6 14.7%	167.7 28.9 
5/20/2004	196.8 14.7%	167.9 28.9 
Average	196.7 14.7%	167.8 28.9


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## CharacterZero (May 19, 2004)

*after the shower readings:*



rapwithtom said:


> OK I am hesitant to post this because I fear you all will realize that I have way too much time on my hands, but here goes anyway:
> 
> I got my Tanita scale last spring and noticed some of the variability issues you all are discussing. To get my hands around it, one I woke up one morning and weighed myself a bunch of times...see the below table.
> 
> ...


are you drying your feet properly? this brings up an interesting point in foot health- do dry, cracked winter feet aftect the reading? Do wet showery feet affect the reading?
Which is closer to your actual %age you think? How do your feet look before the shower?

I just go a TANITA from Performance for half off and have been using it. I will get some postings up with my info soon!


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## bike4miles (Nov 14, 2004)

litespeedblur said:


> Are any of the scales more reliable than others. Does it make a difference what brand I buy?


I got one for $40 at Target and it doesn't go below 5%!!!! Thats a big problem for men. As a result I know I am really lean if it read ERROR LOL


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## GspotRider (Jan 21, 2004)

I have a Tanita BF scale and I found it frustrating how the percentages were so variable day to day. 

Here is what I did to get useful information:
First thing in the morning, after a pee and poo, not showered yet (moist skin changes readings: also do not wet bottom of feet). I would take the first reading (if you try a second or third reading it can be different than the first...after awhile I realized taking the first reading was just fine), and write down the weight and fat %. After you have recorded the information for a week, take the averages of all the weights and percentages. You end up with xxx [email protected] xx%: I would take the percentage and calculate the lean and fat body mass for that week. The numbers you get averaged over a week is fairly consistent and you can actually see if you are gaining muscle (or losing it) verses fat mass. 

If you try to make sense of the readings given on any given day...I would say it is almost useless for accurate tracking of training progress.

Hope this helps.
Alan


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## rapwithtom (Feb 26, 2004)

*No, it's accurate*

What I think from my little study is that the scale is very consistent.

For weight, it's accurate all of the time. Any fluctuations in measured weight are also fluctuations in my weight - mostly likely it's different amounts of hydration. Also I have leared that carbos take lots of water to digest...for instance a pasta dinner will be comfortably accompanied by a lot of water, and that that will show up on the scale for a day or so.

For bodyfat, the Tanita manual suggests mid-afternoon, not following any meals, and not overly cold. That is in fact when it is most accurate for me. And, as I said, it's very repeatable day after day.

As for the prior comment about having wet feet after the shower, that doesn't happen with me as I have to walk across carpet to get to the scale.


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## UCFJosh (Jan 2, 2003)

FWIW, Bed Bath and Beyond has a Tanita scale for $30, and if you find the omni-present 20% off coupon in your mailbox it can be had that much cheaper. It does say that it's not designed for high-performance athletes, but it seems to work just fine for me (not that I qualify as high performance).

Talking to some more knowledgeable folks about this stuff, the consensus was that while these scales may not be 100% accurate, they're generally consistent enough over the long run to determine if you're getting leaner and by about how much.


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## alma10 (Jan 9, 2017)

*body fat scale*



dirkfh said:


> How does hydration affect the output on a body fat scale and best waist trimmer? When is the most accurate time of day to check your body fat? I have been told the best time is the first thing in the morning before any food intake. Is this true?
> I have noticed that if I have a few beers, the next morning my body fat reading is higher than I suspect it should be. Also, I just returned from mexico with a slight bid of Monetzuma's revenge. This has dehydrated me quit a bit. My body fat has shot up approx 2%.
> 
> Thanks for input.
> ...


Hello
One problem with body-fat scales is that they are often inaccurate. Many variables affect the results, including how hydrated you are, when you last ate and exercised, and even whether your feet are highly calloused or dirty, as well as the type and quality of the product itself. Studies have found that different body-fat scales produce widely varying readings and that these often differ from standard methods of fat measurement


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## roseadam (Mar 7, 2017)

I just get my body weight scale, and i am learning how to use it.


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## hammonjj (Jun 29, 2016)

Pro tip I learned while racing in college from some really good physiologists in my area (I went to CU Boulder):


Get your scale and begin recording readings, I prefer first thing in the morning after I pee and shower.
Get a DEXA scan and compare it to your numbers from the scale.
If you've got the cash, do this a couple of times over the span of several months to ensure accuracy

In the end, it doesn't really matter if your scale is accurate or not. What matters is that it is *consistent*. As long as you know when it says you lost 0.5% body fat that you actually lost 0.5% body fat, then you can correlate that back to your DEXA scan numbers to know your true body fat.


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