turtle4499 t1_j55h6ux wrote
Reply to comment by OrneryLawyer in The Benefits of Taking Vitamin D Might Depend on Your Weight | A reanalysis of a large trial found overweight and obese people might metabolize vitamin D supplements differently, leading to lower circulating levels by Hrmbee
And when you make a study where you don't get pictures of the 10k people in it just using BMI doesn't give you the visual information. Congrats you figured out the problem.
BMI has a variable positive predictive value understanding what ranges are good for what situations is important. You would not want to use the same scores for screening patients that you would for measuring risk factors of obesity.
The closer you are to the lower bound there is a reduction in confidence. Which is why in research associating things related to being fat you don't use the 25-30 cutoff because it has too many false positives. Which systematically biases that population to have understated risks of being overweight. Studies that use better adjusted obesity numbers have confirmed this effect.
BMI at a cutoff of 25 is not intended to have low false positive rate its intended to have low false negative rate. Thats why its called a SCREENING TEST. Because almost 100% of people with obesity will have a BMI above 25 that includes many people particularly in the 25-30 range that are not obese. The range that is used is purposefully over capturing because that leads to better screening.
I am really invested in stressing the proper use of BMI. Because using it incorrectly is what causes people to ignore the number out of hand. This is a science sub where people discuss science like proper understanding of the statistical meaning of a BMI score.
OrneryLawyer t1_j55mg3n wrote
You are overthinking this. If a patient stands in front of you with a 30 BMI, will you be able to tell at a glance if the person is obese or not?
What causes people to ignore the number out of hand is not "incorrect use of BMI," it's self delusion.
Hugh-G-Rection-Jr t1_j55p008 wrote
Maybe someone hurt him with the BMI? I mean you need serious mental gymnastics to go over the point and overcomplicate a basic information that much… “incorrect use of BMI” and the whole study thing really nailed it for me, from where I am only fatasses that can’t cope with being fat say crap like that. Look I know this sounds hard but the people who made this stuff know a lot better than someone on reddit who is fixating on a borderline score that would give a false pozitive/negative, really man? Really? You think people with a bmi of 25.2 are going to go insane because they are classed as overweight (25-30 means overweight, like in a little bit over? not obese or going to die just a little fluffy?). I hope in the next comments he gets what screening test actually means and stop saying 25-30 is obese, please link me where cdc says that on the BMI 25 is obese not overweight also that obesity starts at 25 not 30 (TWO TOTALLY DIFFERENT THINGS) and I’m giving in my practice licence tomorrow morning. Please tell me all studies are perfect and please tell me a serious study where if there even aren’t pictures you don’t have staff to evaluate the subjects.
Hugh-G-Rection-Jr t1_j55pfaj wrote
My bad, “society that bases too much on calculus and not enough on statistics” - while shitting on a statistic discovered and worked upon from 1850 while citing what fits the anti dr, anti scientists “i know better without having the slightest ideea what the numbers I’m ready represent” is pretty much explanatory to why. Also the real reason why that number is the way it is isn’t because false results, look down the street and tell me 3/5 people aren’t fat…
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