body fat scale and monitor - which one really works? - RedFlagDeals.com Forums (2025)

I've been pouring over Amazon reviews looking for a good body fat scale and monitor, but one concern keeps popping up.

Some have claimed that these body fat scales are just using BMI calculations based on your inputted height to give you a body fat reading. The legit body fat scales use biomedical impedance analysis (or BIA = sending a weak electric pulse through the body).

Others have claimed that some of these scales, even the ones that use BIA, are inaccurate vs. something like a DEXA scan which is suppose to be the "gold standard." This is less of a concern for me as long as a body fat scale is consistent in its readings of me.

My purpose for buying a body fat scale is a quick and easy way to consistently, not necessarily accurately but of course that would be nice, track changes in body fat. I've lost 50+ lbs of overall weight but I'm at the point I no longer want to track just weight loss, but also body fat loss and muscle gain. I don't see me getting into calipers.

Any suggestions for a legit body fat scale that actually uses BIA would be great!

Thank you!

I just got a cheap $30 Renpho, does the job, takes AAA so I can haz it forever...
These things aren't known for accuracy. If you want to know your bodyfat %, just use the eyeball test.

I did a DEXA, waste of money, good for curiosity though.

I have this impedance based one:

https://www.amazon.ca/Omron-HBF-306C-Fa ... B000FYZMYK

It's not super accurate - it'll change every day based upon levels of hydration, how much i've pooped, etc. That combined with weight fluctations get all very confusing.... and it must have some crappy age lookup table because overnight my BF jumped up on my birthday (when my age changed from 39 to 40)....it's a bit more fancy than just BMI, as when I actively cut, I do see a downward trend even though my scale weight doesn't change immensely.

However I use it for overall trend monitoring rather than the absolute values....that in combination with how my clothes fit and the pictures like the poster put up above....

There's some online calculators that use different body part measurements that seemed fairly accurate. (when i compared my impedance one vs the results from these calculators).

https://www.aleanlife.com/body-fat-calculator/

https://www.fitmatic.com/body/calculato ... calculator

None of them works properly.

When I was still an athlete, my trainer/coach actually measured it using pinch calipers.

4/5% on shoulder/upper rib area and <10% on belly area … those were the good ol’ days

jacobins wrote: ↑
Others have claimed that some of these scales, even the ones that use BIA, are inaccurate vs. something like a DEXA scan which is suppose to be the "gold standard." This is less of a concern for me as long as a body fat scale is consistent in its readings of me.

My purpose for buying a body fat scale is a quick and easy way to consistently, not necessarily accurately but of course that would be nice, track changes in body fat. I've lost 50+ lbs of overall weight but I'm at the point I no longer want to track just weight loss, but also body fat loss and muscle gain. I don't see me getting into calipers.

No one is going to routinely get a DEXA scan.

If you get any BIA body fat scale, and just use it consistently at the same time (e.g. ideally in the morning after waking up and before eating, then you will get a consistent trend measurment.

I've had Tanita body fat scales for over 20 years. I find them relatively accurate (compared with calipers) and good enough for daily use.

https://www.tanita.com/en/body-water-mo ... at-scales/

multimut wrote: ↑If you get any BIA body fat scale, and just use it consistently at the same time (e.g. ideally in the morning after waking up and before eating, then you will get a consistent trend measurment.

Yup trends more important than absolute precision.

batcave wrote: ↑I've had Tanita body fat scales for over 20 years. I find them relatively accurate (compared with calipers) and good enough for daily use.

https://www.tanita.com/en/body-water-mo ... at-scales/

On Amazon, lost in translation?

Tanita Body Composition Monitor BC-705N-WH (White) Ride Easily Measured in Capitalist Function
4.24.2 out of 5 stars (13,499)
$103.68

Yeah, I didn't feel my DEXA scan was accurate. Regret spending $70 on it. Though I did end up cutting afterwards after my shock. So maybe it was worth it.
U of T used to run hydrostatic testing, that's accurate as well. Used to be $100 twenty years ago, don't want to know how much it is now, if they still even do it.

I used calipers in university, yeah, large range. It's really just a consistency game. Now I just use the eyeball test.

ADenariusSaved wrote: ↑Yeah, I didn't feel my DEXA scan was accurate. Regret spending $70 on it. Though I did end up cutting afterwards after my shock. So maybe it was worth it.
U of T used to run hydrostatic testing, that's accurate as well. Used to be $100 twenty years ago, don't want to know how much it is now, if they still even do it.

There really is no reason for an average person who is not a elite athlete to need to do a DEXA scan just to measure body composition (unless you are getting measured regularly, what's the point).
But having said that, it is the most accurate measurement. Hydrostatic testing is in theory also highly accurate, but in practice it's a lot harder to do hydrostatic accurately (person needs to fully expel all air, and testing is hard to do) . Yes, the more accurate methods, such as DEXA, often produce higher body fat percentages than more simple methods, but it's not the absolute number that matters.

This blog explains why DEXA is more accurate, and why it may produce higher body fat values than more simple methods:
https://dexalytics.com/news/higher-values-dxa/
DEXA scan is the most accurate measure. way to determine body composition, as it directly measures fat, lean skeletal and bone masses.
This significantly reduces the margin of error because DXA doesn’t calculate body fat percentage from body density equations or require extra calculations that use non-specific equations like two-component methods. More importantly, DXA determines lean skeletal, fat and bone masses in various regions of the body versus assuming body composition is the same throughout the entire body as is done in the two-component method. Therefore, by determining regional body compositions as well as determining lean skeletal, bone and fat masses rather than making assumptions about bone and muscle, the percent fat is a little higher than two-component methods of determining body composition. "

Precision is determined by the coefficient of variation between measurements. A measurement is more precise if the limits on the coefficient of variation are low and narrow (see figure above). Precision, both when tracking an individual and comparing multiple individuals, is critical if you plan to compare athletes. For example, you could have two athletes that are 20% body fat on DXA, but using a two-component method one is 12% and the other one is 17%. The decisions made with these athletes from a training or nutrition perspective may differ based on the results of the two-component method, but the more accurate and precise DXA methodology indicates the fat mass is actually the same.

When we started working with athletes we knew this would be one of the biggest challenges. The issues include a negative connotation with percent body fat and explaining to coaches and athletes what these numbers mean and why they are different. If individuals are used to seeing values from skinfolds, or another two-component method, there can be a little bit of “sticker shock” when discussing the body composition results from a DXA.

The goal should be to have accurate and reliable information, which can then be used to both track an individual athlete over time ....