6 ms·

Electrical impedance has been shown to be absolutely trash in accurately predicting bf%. I've used both Garmin's and Fitbit's smart scales, which are supposed t

Electrical impedance has been shown to be absolutely trash in accurately predicting bf%. I've used both Garmin's and Fitbit's smart scales, which are supposed to be top-of-the-line, and compared to DXA... the numbers aren't even close. Most people report similar experiences.

actuator 6y ago
That's not something you can have at your home though, no? The DEXA/DXA scans machine I know of are something you can't keep at the comfort of your home. In my personal experience I have found impedance ones to be fairly accurate(~10%, BF range 10-16) and for most people the accuracy of full body ones is good to have a general idea about their body. Probably when you reach sub 10 levels, accuracy matters more. Btw, here is the link to studies they give: https://inbodyusa.com/studies/ https://inbodyusa.com/studies/
- parliament32 6y ago
  I've also found about a 10-point discrepancy. There's a huge difference between 15% and 25% bf.. one is approaching athletic while the other is obese. DXA is definitely less convenient, but there's no real reason to test your bf% daily (just like weighing yourself daily isn't productive, you need to look at average changes over time). Considering the amount of time it takes to significantly change your bf%, twice a year testing would be plenty.. and would probably cost you the same amount as this subscription service.
  - whatch 6y ago
    Maybe weighing daily IS productive, but looking at the result daily is not :)
calvano915 6y ago
Hydration and other factors affect accuracy of impedance body fat estimation. So consistency is key, like measuring at the same time in the same conditions (for myself, after waking and before any consumptions of food or water) daily. Still, absolute measurement will not be as accurate as DXA, hydrostatic, skin calipers, etc. However, for relative changes over time when consistently measured, impedance works just fine (trending upward or downward). I'm very skeptical of their claim that the photo measurements are more accurate than other means, but perhaps they've done massive validation of their methods and have achieved adequate reliability and validity.
- parliament32 6y ago
  >for relative changes over time when consistently measured, impedance works just fine Agreed, but for change over time it's just as accurate as skin calipers... which don't require an investment or subscription service.
  - calvano915 6y ago
    While skin calipers are most affordable regarding equipment, the reliability is poor unless the person measuring is very consistent (well-trained and/or experienced for consistent pinch/folds). Calipers also will be inconvenient and possibly unaffordable for many because access to the person measuring is necessary whenever you want an updated measurement. In my view, impedance evens out with calipers because of the convenience of impedance measurements over time. I just stand on the scale for a few seconds every morning, and I have stats synced that give me a good enough idea of my status (bonus for the added understanding of my hydration which calipers won't do). There's no cost or subscription for my scale aside from initial purchase (Withings aka Nokia Body Cardio), and it is regularly available for as low as $99 on sale. So after a couple years and hundreds of measurements the cost is negligible given the benefit. If I had someone regularly accessible to do caliper measurements, I would have it done to compare regularly but still continue with impedance because it's so convenient to do and track.
    - parliament32 6y ago
      It's still useless if the data is garbage, which it really is. I had DXA scans done every half year for the last few years, and I've owned a few smart scales in that time (first Fitbit, then Garmin). DXA has shown me consistently dropping bf% (17.8%, 15.0%, 13.1%, 11.2%) while the scales (taking monthly averages) are all over the place (10.1%, 11.1%, 11.6%, 10.0% for the same months the scans were taken in). Impedance can show you a ballpark (and we're talking a wide, 10%ish ballpark) of where you are, but honestly you're probably better off just looking in the mirror and comparing to images online. I only mentioned calipers because they'd at least show you trends, which is where impedance seems to fail. Impedance is simply a poor way to measure bf%. Hydration might be a different story though. I'd recommend you do yourself a favor and just spend the $100 annually to see where you're at.
nradov 6y ago
I can confirm that the Withings Body+ scale body fat measurement is also total garbage. For me it reads several percent lower than a DXA scan, basically just a vanity number for people who want to believe they aren't fat. The readings also fluctuate a lot based on how well hydrated I am.

actuator 6y ago

That's not something you can have at your home though, no? The DEXA/DXA scans machine I know of are something you can't keep at the comfort of your home. In my personal experience I have found impedance ones to be fairly accurate(~10%, BF range 10-16) and for most people the accuracy of full body ones is good to have a general idea about their body. Probably when you reach sub 10 levels, accuracy matters more. Btw, here is the link to studies they give: https://inbodyusa.com/studies/ https://inbodyusa.com/studies/

parliament32 6y ago
I've also found about a 10-point discrepancy. There's a huge difference between 15% and 25% bf.. one is approaching athletic while the other is obese. DXA is definitely less convenient, but there's no real reason to test your bf% daily (just like weighing yourself daily isn't productive, you need to look at average changes over time). Considering the amount of time it takes to significantly change your bf%, twice a year testing would be plenty.. and would probably cost you the same amount as this subscription service.
- whatch 6y ago
  Maybe weighing daily IS productive, but looking at the result daily is not :)

calvano915 6y ago

Hydration and other factors affect accuracy of impedance body fat estimation. So consistency is key, like measuring at the same time in the same conditions (for myself, after waking and before any consumptions of food or water) daily. Still, absolute measurement will not be as accurate as DXA, hydrostatic, skin calipers, etc. However, for relative changes over time when consistently measured, impedance works just fine (trending upward or downward). I'm very skeptical of their claim that the photo measurements are more accurate than other means, but perhaps they've done massive validation of their methods and have achieved adequate reliability and validity.

parliament32 6y ago
>for relative changes over time when consistently measured, impedance works just fine Agreed, but for change over time it's just as accurate as skin calipers... which don't require an investment or subscription service.
- calvano915 6y ago
  While skin calipers are most affordable regarding equipment, the reliability is poor unless the person measuring is very consistent (well-trained and/or experienced for consistent pinch/folds). Calipers also will be inconvenient and possibly unaffordable for many because access to the person measuring is necessary whenever you want an updated measurement. In my view, impedance evens out with calipers because of the convenience of impedance measurements over time. I just stand on the scale for a few seconds every morning, and I have stats synced that give me a good enough idea of my status (bonus for the added understanding of my hydration which calipers won't do). There's no cost or subscription for my scale aside from initial purchase (Withings aka Nokia Body Cardio), and it is regularly available for as low as $99 on sale. So after a couple years and hundreds of measurements the cost is negligible given the benefit. If I had someone regularly accessible to do caliper measurements, I would have it done to compare regularly but still continue with impedance because it's so convenient to do and track.
  - parliament32 6y ago
    It's still useless if the data is garbage, which it really is. I had DXA scans done every half year for the last few years, and I've owned a few smart scales in that time (first Fitbit, then Garmin). DXA has shown me consistently dropping bf% (17.8%, 15.0%, 13.1%, 11.2%) while the scales (taking monthly averages) are all over the place (10.1%, 11.1%, 11.6%, 10.0% for the same months the scans were taken in). Impedance can show you a ballpark (and we're talking a wide, 10%ish ballpark) of where you are, but honestly you're probably better off just looking in the mirror and comparing to images online. I only mentioned calipers because they'd at least show you trends, which is where impedance seems to fail. Impedance is simply a poor way to measure bf%. Hydration might be a different story though. I'd recommend you do yourself a favor and just spend the $100 annually to see where you're at.

nradov 6y ago

I can confirm that the Withings Body+ scale body fat measurement is also total garbage. For me it reads several percent lower than a DXA scan, basically just a vanity number for people who want to believe they aren't fat. The readings also fluctuate a lot based on how well hydrated I am.