The bioelectric impedance scales, as I have been consistently saying the entire time. I have no expertise or opinion about their other products. It's entirely plausible that they may furnish you with a functional blood pressure device, but to be honest I am reticent to support any company that offers scam products alongside their legitimate options.

Why are they used in research?

Whoever severely misled you into believing that this company's products are some important cornerstone of scientific research should be totally exiled from your consideration. Hopefully it's only a result of their ridiculous marketing and this will be a simple correction

Do you have any source on why they are entirely unusable?

You are the one claiming they are not only usable but scientifically important, please feel free to furnish any sources proving they can tell your bf% better than +/-5%. The reason you can't find any is because none of the the methods, including DEXA scans, are functionally accurate at all. The entire field exists to scam people who are trying to better themselves

[–] ToxicWaste@lemm.ee 3 points 15 hours ago (1 children)

man i largely agree with what you are saying and there are tons of useless 'fitness' products.

but you cannot claim to be "happy to delve into the subject" and when asked for sources simply deflect. you have to remember, that absence of evidence is not evidence of absence.

so if you want to believabily present yourself as an expert on the subject and have such an absolute standpoint - you need to present some good reasons. otherwise you have to soften your standpoint to something akin to: "there has ben no proof of its reliability". everything stronger seems disingenuous.

[–] Carnelian@lemmy.world 1 points 12 hours ago (1 children)

The irony being that these companies pushing the scam products are themselves presenting as experts with an absolute standpoint. A standpoint which of course involves paying them a bunch of money to acquire extremely specific capabilities which are totally unfounded in reality.

Which makes you raising this principle very interesting: absence of evidence is not evidence of absence. You are misapplying the concept.

If I said, "there are no bears in the woods", then yes now I have to carefully and thoroughly demonstrate this. An impossible task in fact, since I simply cannot check behind every tree. Indeed, even if I did check every tree, bears move around, and I could miss one despite it really being there! Therefore it is wrong for me argue such a strong negative, and it would be proper to instead say, "I haven't seen any bears". I'm with you on this.

Now imagine if some company says, "The woods are full of dangerous bears! You should buy our bear repelling hat!", and I say, "This is actually a well known scam tactic, and this company is just selling useless hats. Another company is selling bear pants, and yet another company is doing shoes. It's all bullshit. Don't waste your money. Use proven methods such as bear spray."

Now in this situation, sure, you can try to start a semantic argument with me about whether or not it is philosophically just for me to state "the hats are useless" in such absolute terms. Structurally, that snippet is the same, yes? A strongly phrased negative. Doesn't it run into the same problem?

It turns out, no. You see, the scam company at this point in time has already made the claim that the hats are useful. This is a claim that absolutely requires a source. The fact that they are forcefully presenting this claim despite having no source is itself proof that the product is a scam. By the very nature of the phenomenon in question, there needs to be a source before they make the claims.

In other words, once a company is claiming that an effect is present in fact, then absence of evidence becomes evidence of absence. Because they are simply fucking lying lol. We don't need to keep doing this every week with every company that runs the same scam template with a different article of clothing.

Anyway, you wound me with your incorrect assertion that I have deflected anything, when I directly answered the questions I was asked and provided further information on things to look into, such as DEXA scans. Anyone bothered by my strong language will quickly discover the reality that every reputable study ever performed relating to these devices recommends against them.

TL;DR: Our study shows that although smart scales are accurate for total body weight, they should not be used routinely to assess body composition, especially in patients with severe obesity.

[–] ToxicWaste@lemm.ee 1 points 2 hours ago

you don't seem to get my point entirely, so ill try to explain it here. your standpoint seems to be:

body fat cannot be determined by impedance
the measurements are that unreliable that the mere presence of the measurement hurts more than it helps

you present these points as expert, not as your opinion. in the comment thread you write: "I’m happy to delve into this subject in as much depth as you may be interested in". when someone asks you for sources, supporting these points (presumably because they are interested) - you deflect and take a combative stance. it is deflection, as you ask the person trying to learn something, to find proof that your point is wrong. since you (initially) did not provide sources for your points - you seem to take the absence of evidence (from the companies selling these) as evidence, that it can not work and will cause harm.

This line of argumentation makes me second guess your motivation. even though i agree with the overall viewpoint. i am not asking you to prove it is a scam. as you mentioned it is tedious and wasteful to prove every new scam attempt false. so if you shift your argumentation just slightly (which you did in your reply to me), the whole second guessing of motivation won't occur:

The companies selling these products don't provide any proof, that these scales work as advertised
especially in medicine it is required to proof, that the benefits hugely outweigh the drawbacks
who is more likely to tell you a falsehood: the person actively trying to sell you something or the one not selling anything?
- -> be more skeptical of the person with a motivation to mislead you and ask them to provide proof and sources

these points are a very strong argument IMO and don't require to do any more research. but they seem much more genuine as you don't appear go back on wanting to discuss the subject and don't take a combative stance towards the person probably trying to learn something.