eli5 how can a bathroom scale determine the body fat, water content and “dry” bone mass just from passing some electrical current?
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It can’t, if it was that easy would there be no reason for that huge amount of papers there has been done in the subject. Only a doctor can correctly estimate your numbers.
Easy answer. It can’t.
It’s a very, very rough estimate derived from how conductive the path from one leg to the other (through the pelvis) is. It allows it to calculate an estimate of the amount of subcutaneous fat… But that has huuuuuge error bars: gender, age, individual variations in fat distribution, skin conductivity, how wet or soapy your skin is when using the scale…
These are basically worthless for the absolute number. The only thing you can use them for is track changes over time to see whether you’re going in the right direction, but that’s it.
I had one that clearly just estimated based on height and weight.
(We tested it with different people with vsibly different muscle mass. It also changed depending on what gender you told it you were)
The number it comes up with is generally meaningless. It is an estimate based on how the electricity moves through your body. It CAN be useful information, but only in very specific circumstances. Basically, if you are on a regimented diet AND hydration program, and you measure at the same time and circumstances every day (e.g. just after waking up and going to the bathroom). It can be a useful gauge of progress. In almost any other circumstance, it’s worthless.
My gym just got a Boditrax machine, which I believe is a much more advanced version of this. is it anymore accurate?
It messures the resistance and does calculations based on programmed data set it has . Its not going to be 100% acurate but good enough for anyone that isnt doing serious science. If you are planning to lose weight you can use it to track progress.
For people that say that its “useless” becouse they dont give accurate information have also not figured out that those automatic bloodpressure mesurements that hospitals uses are also not accurate but an estimation based on the mean arterial pressure.
Mine isnt even that accurate at weight, and thats all its supposed to do.
I dont care about exact ounces anyways. Just wanna keep the lbs in line. Thankagiving holiday they have been… going up. Lol
Some brands/scales are MUCH better than others. Some pass multiple signals through the body along with having both hands and feet sensors, etc.
I have one that is consistent both with its own reading over many days, and is also consistently close to DEXA results as well. As someone else noted the one I have is probably within ~ 2% of its own readings.
But it’s not one those $20 specials on Amazon.
I have also used one of those cheap ones before and it didn’t give consistent results even with multiple tests just seconds later, sometimes having wildly different results, it was completely useless. 🤦♂️
They can’t. They’re novelty items that use a few basic datapoints like weight, gender etc. to look up a table of statistical averages.
Reminds me of shitty weight loss MLM I was going to that had this scale and they were weighting me like at 7 pm because they had these meetings late and I loved to wear huge oversized pants and hoodies, also I love to drink water throught the day, especially filtered water with ice cubes <3 and wondered if it’s really accurate if I ate dinner like two hours ago + snack + I drank like 3 liters of water + my clothes lol, it just didn’t feel like accurate to me ?
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