Body fat % > Body mass Index

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  • Codyroo5539
    Codyroo5539 Posts: 3 Member
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    CasperNaegle wrote: »
    The BMI is really for large swaths of population. Using it for individuals is really useless in my opinion. I'm borderline Obese at 190 and 5'8". It assumes you are a very low muscle massed individual and a very significant portion of your weight is coming from fat.

    Exactly what CasperNaegle said. BMI was not meant for individuals. It was meant for entire populations. I also "loathe" when people ask me my weight and then compare it to BMI. For me (5' 9") my BMI says I need to be 168 lbs to be below "overweight". However, when I weigh 168 lbs, my family is begging me to eat, because my face is extremely drawn and I look undernourished (Body fat was between 17% - 18% and my waistline was 33"). I have bigger, muscular thighs and calves, and likely thicker bones, and these wreak havoc on the scale.
  • daynaxxanne
    daynaxxanne Posts: 77 Member
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    I find body fat calculators to be rather inaccurate. That being said, I have never done the specific method mentioned. I just find them inaccurate because I'm wearing a size 2-4 and its telling me I'm at risk of being over weight (I'm 5'5" , 138lbs). I had also lost two inches off my waist and my body fat percentage didn't even drop a fraction of a precent.
  • eldamiano
    eldamiano Posts: 2,667 Member
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    McCloud33 wrote: »
    @eldamiano because that's what it is primarily used for! It's not that much more difficult to break out the tape measure and take a few waist measurements. It's just not good math coming from an engineer. The algorithm was developed by an economist to fit a group of data points as they related to an entire population. He's even quoted as saying that it should never be used to assess individual health!

    Again, why is that the fault of BMI as a guide? The OP referred to it as a vague algorithm, without any reference to insurance premiums, hence my post. This is even though I disagree with what it is used for. I have heard of BMI thousands of times in general use without it being in the context of insurance.
  • Jruzer
    Jruzer Posts: 3,501 Member
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    barbarinc wrote: »
    It is a very vague algorithm combining height and weight.

    BMI = [mass (kg)]/[height (m)]^2

    That's hardly vague.
  • senecarr
    senecarr Posts: 5,377 Member
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    McCloud33 wrote: »
    Hornsby wrote: »
    BMI works fine for 95% of the masses. Of course, there are outliers, but recommending BIA instead isn't the answer either. Those aren't even remotely accurate usually.

    I would disagree with this in part. I think it works for 95% of the population telling you if in fact you are obese. I think that number drastically reduces when you talk about "overweight" (maybe 75%) and again when you're talking about "healthy" BMI. The reason I think that it's off for the healthy category is that there are so many people today that are "skinny fat" with our sedentary lives and have higher than recommended fat levels even though their overall weight is "normal". I do agree that BIA is not the answer either though just because it's inaccurate. But BF testing in general is what I would recommend. In order of accuracy/reliability I would say DEXA, Hydrostatic, BodPod, tape measure/scale combo, mirror, BIA. Really, the only thing I feel BIA is good for is trend tracking. If you get one of the more reliable methods done first and calibrate your BIA to match that output, I think it can have a place in your tracking metrics.

    Actually, BMI is 100% accurate at telling someone they are obese or overweight. BMI is used to define those terms, medically. It becomes less clear below obese BMI's if the BMI is a predictor of health, or of body fat percentage. Which is fine, nothing in medical literature says that overweight is a guarantee a person is unhealth, or that normal weight is healthy.
  • senecarr
    senecarr Posts: 5,377 Member
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    Codyroo5539 wrote: »
    CasperNaegle wrote: »
    The BMI is really for large swaths of population. Using it for individuals is really useless in my opinion. I'm borderline Obese at 190 and 5'8". It assumes you are a very low muscle massed individual and a very significant portion of your weight is coming from fat.

    Exactly what CasperNaegle said. BMI was not meant for individuals. It was meant for entire populations. I also "loathe" when people ask me my weight and then compare it to BMI. For me (5' 9") my BMI says I need to be 168 lbs to be below "overweight". However, when I weigh 168 lbs, my family is begging me to eat, because my face is extremely drawn and I look undernourished (Body fat was between 17% - 18% and my waistline was 33"). I have bigger, muscular thighs and calves, and likely thicker bones, and these wreak havoc on the scale.

    How can it be accurate for populations if it doesn't have at least a modicum of accuracy at individual level?
    You're speaking as if 17-18% is unhealthy low, assuming you have an accurate source for the number. People's perceptions of what is too thin is rather skewed these days by a population where the majority are overweight or obese.

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