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do those body fat scales work?

ALEXIS_DH

Tirelessly Awesome
Jan 30, 2003
5,783
426
Lima, Peru, Peru
depends a lot.
always do it at the same time. preferably afternoon, before working out.
if you take antidepresants or other stuff, they might not be acurate at all.
some people like them a lot, but i prefer calipers myself.
 

Wumpus

makes avatars better
Dec 25, 2003
8,163
154
Six Shooter Junction
Body Fat Analyzers: Tanita Scales. Tanita scales leg-to-leg version of bioelectrical impedance analysis does have the ability to effectively determine body fat levels that are similar in accuracy to those of both the DEXA(Dual Energy X-ray Absorptiometry) and hydrostatic weighing(dunk tank) methods.

http://www.halls.md/fat/bibliography.htm
 

ultraNoob

Yoshinoya Destroyer
Jan 20, 2007
4,515
1
Hills of Paradise
I've been through the dunk tank to get the best measure of my body fat (I was a little depressed afterwards... that's beside the point), but in the same session, I was measured with calipers and a bathroom bodyfat scale.

The Calipers were only 1-2 percent points off of the dunk tank results. The bathroom scale was under by 5 percent points until they wet my feet before stepping on the scale. With wet feet, the bathroom scale matched the caliper measurments almost exactly.
 

bean

Turbo Monkey
Feb 16, 2004
1,338
0
Boulder
I've heard before that in order of accuracy it goes dunk tank, scales, calipers. Mostly because there's so much variability in the person using the calipers.
 
Mar 26, 2007
63
0
New Zealand
yeah ive heard of the 3 diff methods, and i know that when i got mine done on scale thingees at the gym they told me it could be out by 2% up or down, and that callipers are more accurate, although some people doing calliper measurements dont take into account thighs and thats a huge variable.

If you want a really really accurate idea i guess you could do all 3 ... and let us know how it goes :-) The dunk tank thingee ive heard is quite close, but i think they do all vary depending on the operator as someone else said.
 

jacksonpt

Turbo Monkey
Jul 22, 2002
6,762
0
Vestal, NY
Well, I picked one up last night, so now I've got something else to work on/think about.

Anyone know how body fat percentages translate to body weight? i.e. what does decreasing my body fat by 2% mean to my overall weight, that sort of thing? I'm sure it's different for everyone, but are there any general rules of thumb?
 

Wumpus

makes avatars better
Dec 25, 2003
8,163
154
Six Shooter Junction
Well, I picked one up last night, so now I've got something else to work on/think about.

Anyone know how body fat percentages translate to body weight? i.e. what does decreasing my body fat by 2% mean to my overall weight, that sort of thing? I'm sure it's different for everyone, but are there any general rules of thumb?
If you decrease your body fat percenentage by 2%(20% Body fat to 18%), it will be a corresponding 2% decrease in weight.
 

mogulskr

Monkey
Aug 28, 2002
641
0
NH
That assumes that my water weight stays the same, right?
The one that I have also does percentage of water. So I will get a reading like this

177 - weight
12% - body fat - is usually right between 11 and 12
57% - this varies by 1 to 2 percent.

I also do it in the morning after the shower, it says to do it with damp feet.
 

jacksonpt

Turbo Monkey
Jul 22, 2002
6,762
0
Vestal, NY
The one that I have also does percentage of water. So I will get a reading like this

177 - weight
12% - body fat - is usually right between 11 and 12
57% - this varies by 1 to 2 percent.

I also do it in the morning after the shower, it says to do it with damp feet.
Yep, that's the way mine works too.

Right now I'm 159.2lbs, 17% body fat, 60% water weight. I'd like to get those first two numbers down, not really sure what the water weight number means. Could it somehow suggest or hint at hydration levels?
 

binary visions

The voice of reason
Jun 13, 2002
21,834
705
NC
If you decrease your body fat percenentage by 2%(20% Body fat to 18%), it will be a corresponding 2% decrease in weight.
Losing body fat through exercise will also be building muscle, though, so you can lose body fat and actually gain weight or remain the same. It won't be 1:1 unless your muscle mass & water content stay constant, right?
 

ALEXIS_DH

Tirelessly Awesome
Jan 30, 2003
5,783
426
Lima, Peru, Peru
Losing body fat through exercise will also be building muscle, though, so you can lose body fat and actually gain weight or remain the same. It won't be 1:1 unless your muscle mass & water content stay constant, right?
i´ve been told, by a dr, its almost impossible (naturally) to lose body fat only.
 

jacksonpt

Turbo Monkey
Jul 22, 2002
6,762
0
Vestal, NY
I don't understand these stupid things. Granted I've only had it for 3 days and I got it to track more long term changes and averages, not day-to-day changes, but...

The first 2 days I had it all readings were exactly the same, regardless of time of day (which makes some sense):
- weight: 159.2
- body fat: 17%
- water weight: 60%

I get on it this morning, same routine as the last couple of days...
- weight 156.2
- body fat 17.1
- water weigth: 59%

Considering my diet and activity levels the last week or so, I don't see how my body weight could have gone down but by body fat gone up. Oh well...
 

binary visions

The voice of reason
Jun 13, 2002
21,834
705
NC
Considering my diet and activity levels the last week or so, I don't see how my body weight could have gone down but by body fat gone up. Oh well...
Your body fat went up 0.1% which I'm sure is well within the error margin for the scale. Your water % went down by 1% so that's a pound and a half right there. Plus the contents of your stomach/intestines.