4 ms·

BMI has been known to be unreliable for almost as soon as it was published, but people clinged to it because they could get some number with absolutely no educa

BMI has been known to be unreliable for almost as soon as it was published, but people clinged to it because they could get some number with absolutely no education and only basic tools on the measuring side. You could do it in the jungle with a tape measure and a weighting board. So the base reasonning was “a somewhat dummy number is better than no number at all”. DXA is 100% better but requires trained personnel and expensive, advanced scanners. I’m not sure it’s a fitting upgrade of BMI…and if a subject can be thorougly scanned, can’t they also get more personal advice and actual assessment of what they are risk of (blood pressure ? heart disease ? diabetes ?) instead of some vague “you’re fat so you should lose weight, we’ll see how you’ll actually die once you’re thinner” ?

lhl 4y ago
There's a lot of misinformation about BMI... Is it perfect? No, in fact for women, it tends to significantly under-report obesity (when defined against fat percentage, officially, obesity is mostly defined by BMI though so of course it's always accurate in that sense). It's actually quite accurate for men though. There has in fact been extensive study on better formulas, and one recent study has proposed Relative Fat Mass, RFM as a new index that does a better job correlating to DXA measurements for all populations: Woolcott, Orison O., and Richard N. Bergman. “Relative Fat Mass (RFM) as a New Estimator of Whole-Body Fat Percentage ─ A Cross-Sectional Study in American Adult Individuals.” Scientific Reports 8, no. 1 (July 20, 2018): 10980. https://doi.org/10.1038/s41598-018-29362-1 https://doi.org/10.1038/s41598-018-29362-1. Someone else mentioned waist-to-height-ratio (WHtR) as a better marker for metabolic health, and I tend to agree that it's superior to BMI: Ashwell, Margaret, and Sigrid Gibson. “Waist-to-Height Ratio as an Indicator of ‘Early Health Risk’: Simpler and More Predictive than Using a ‘Matrix’ Based on BMI and Waist Circumference.” BMJ Open 6, no. 3 (March 14, 2016). https://doi.org/10.1136/bmjopen-2015-010159 https://doi.org/10.1136/bmjopen-2015-010159. If you're also arguing that people should be looking at other markers for metabolic health, sure. If you get an annual checkup, you should get everything you need to calculate your metabolic syndrome markers, which is an excellent way to assess metabolic health: Huang, Paul L. “A Comprehensive Definition for Metabolic Syndrome.” Disease Models & Mechanisms 2, no. 5–6 (2009): 231–37. https://doi.org/10.1242/dmm.001180 https://doi.org/10.1242/dmm.001180.
- makeitdouble 4y ago
  > It's actually quite accurate for men though. No https://pubmed.ncbi.nlm.nih.gov/15807202/ https://pubmed.ncbi.nlm.nih.gov/15807202/ > In this study BMI shows a low reliability as a predictor of individual body fatness, particularly in men and in subjects with a BMI below 30 kg/m2. > waist-to-height-ratio (WHtR) Wouldn't elecricatl impedance analysis yield better results, as we have most of our home weighting board at this point ? I mean, for now a pretty low price we have better device to get approximation than a measuring tape.
  - lhl 4y ago
    > No There's no point to having further factual discussion if you aren't going to read the referenced papers. From the 2018 study I referenced you can see that DXA-positive and BMI-positive correlation was 2,668/2,778 (Table 3), or simply look at Figure 2. And if you say "No" and then link to a 2004 paper using bio-electrical impedance, I don't really know what to say, since BIA is one of the least accurate methods and there's plenty of research comparing indices to gold-standard DXA already. Nickerson, Brett S. “Agreement between Single-Frequency Bioimpedance Analysis and Dual Energy x-Ray Absorptiometry Varies Based on Sex and Segmental Mass.” Nutrition Research (New York, N.Y.) 54 (2018): 33–39. https://doi.org/10.1016/j.nutres.2018.03.003 https://doi.org/10.1016/j.nutres.2018.03.003. In fact, here's a paper concluding recommending BIA shouldn't be used clinically from ... 2004: Buchholz, Andrea C., Cynthia Bartok, and Dale A. Schoeller. “The Validity of Bioelectrical Impedance Models in Clinical Populations.” Nutrition in Clinical Practice: Official Publication of the American Society for Parenteral and Enteral Nutrition 19, no. 5 (October 2004): 433–46. https://doi.org/10.1177/0115426504019005433 https://doi.org/10.1177/0115426504019005433. If you've used a BIA measuring scale at home, you'll see that it fluctuates wildly and serves more of a measure of how dehydrated you are during the day than any other health metric. Ultimately though, I think you're splitting hairs/missing the point. There are tons of bio-markers anyone case use to track their health progress directionally at home. Just pick one and use what you want and stop worrying about what other people are doing. Most people who argue the most against BMI or whatever as a marker already know that they're not as healthy as they should be. And if you don't want to measure anything, if you're an American adult, you can probably just safely assume that you're not (only 12% "metabolically optimal" from 2009-2016 NHANES data): Araújo, Joana, Jianwen Cai, and June Stevens. “Prevalence of Optimal Metabolic Health in American Adults: National Health and Nutrition Examination Survey 2009–2016.” Metabolic Syndrome and Related Disorders 17, no. 1 (November 27, 2018): 46–52. https://doi.org/10.1089/met.2018.0105 https://doi.org/10.1089/met.2018.0105.

lhl 4y ago

There's a lot of misinformation about BMI... Is it perfect? No, in fact for women, it tends to significantly under-report obesity (when defined against fat percentage, officially, obesity is mostly defined by BMI though so of course it's always accurate in that sense). It's actually quite accurate for men though. There has in fact been extensive study on better formulas, and one recent study has proposed Relative Fat Mass, RFM as a new index that does a better job correlating to DXA measurements for all populations: Woolcott, Orison O., and Richard N. Bergman. “Relative Fat Mass (RFM) as a New Estimator of Whole-Body Fat Percentage ─ A Cross-Sectional Study in American Adult Individuals.” Scientific Reports 8, no. 1 (July 20, 2018): 10980. https://doi.org/10.1038/s41598-018-29362-1 https://doi.org/10.1038/s41598-018-29362-1. Someone else mentioned waist-to-height-ratio (WHtR) as a better marker for metabolic health, and I tend to agree that it's superior to BMI: Ashwell, Margaret, and Sigrid Gibson. “Waist-to-Height Ratio as an Indicator of ‘Early Health Risk’: Simpler and More Predictive than Using a ‘Matrix’ Based on BMI and Waist Circumference.” BMJ Open 6, no. 3 (March 14, 2016). https://doi.org/10.1136/bmjopen-2015-010159 https://doi.org/10.1136/bmjopen-2015-010159. If you're also arguing that people should be looking at other markers for metabolic health, sure. If you get an annual checkup, you should get everything you need to calculate your metabolic syndrome markers, which is an excellent way to assess metabolic health: Huang, Paul L. “A Comprehensive Definition for Metabolic Syndrome.” Disease Models & Mechanisms 2, no. 5–6 (2009): 231–37. https://doi.org/10.1242/dmm.001180 https://doi.org/10.1242/dmm.001180.

makeitdouble 4y ago
> It's actually quite accurate for men though. No https://pubmed.ncbi.nlm.nih.gov/15807202/ https://pubmed.ncbi.nlm.nih.gov/15807202/ > In this study BMI shows a low reliability as a predictor of individual body fatness, particularly in men and in subjects with a BMI below 30 kg/m2. > waist-to-height-ratio (WHtR) Wouldn't elecricatl impedance analysis yield better results, as we have most of our home weighting board at this point ? I mean, for now a pretty low price we have better device to get approximation than a measuring tape.
- lhl 4y ago
  > No There's no point to having further factual discussion if you aren't going to read the referenced papers. From the 2018 study I referenced you can see that DXA-positive and BMI-positive correlation was 2,668/2,778 (Table 3), or simply look at Figure 2. And if you say "No" and then link to a 2004 paper using bio-electrical impedance, I don't really know what to say, since BIA is one of the least accurate methods and there's plenty of research comparing indices to gold-standard DXA already. Nickerson, Brett S. “Agreement between Single-Frequency Bioimpedance Analysis and Dual Energy x-Ray Absorptiometry Varies Based on Sex and Segmental Mass.” Nutrition Research (New York, N.Y.) 54 (2018): 33–39. https://doi.org/10.1016/j.nutres.2018.03.003 https://doi.org/10.1016/j.nutres.2018.03.003. In fact, here's a paper concluding recommending BIA shouldn't be used clinically from ... 2004: Buchholz, Andrea C., Cynthia Bartok, and Dale A. Schoeller. “The Validity of Bioelectrical Impedance Models in Clinical Populations.” Nutrition in Clinical Practice: Official Publication of the American Society for Parenteral and Enteral Nutrition 19, no. 5 (October 2004): 433–46. https://doi.org/10.1177/0115426504019005433 https://doi.org/10.1177/0115426504019005433. If you've used a BIA measuring scale at home, you'll see that it fluctuates wildly and serves more of a measure of how dehydrated you are during the day than any other health metric. Ultimately though, I think you're splitting hairs/missing the point. There are tons of bio-markers anyone case use to track their health progress directionally at home. Just pick one and use what you want and stop worrying about what other people are doing. Most people who argue the most against BMI or whatever as a marker already know that they're not as healthy as they should be. And if you don't want to measure anything, if you're an American adult, you can probably just safely assume that you're not (only 12% "metabolically optimal" from 2009-2016 NHANES data): Araújo, Joana, Jianwen Cai, and June Stevens. “Prevalence of Optimal Metabolic Health in American Adults: National Health and Nutrition Examination Survey 2009–2016.” Metabolic Syndrome and Related Disorders 17, no. 1 (November 27, 2018): 46–52. https://doi.org/10.1089/met.2018.0105 https://doi.org/10.1089/met.2018.0105.