> The most notorious of which is BMI; it is practically a category error to infer someone's health or risk by individual BMI, and yet doing so remains widespread amongst people that are supposed to know better.
BMI works fine for people who aren't very muscular, which is the great majority of people. Waist to height ratio might be more informative for people with higher muscle mass.
As a person who has been told I'm "morbidly obese" for decades now, I will say that doctors at almost every level look at your chart not you. I've been told time and time again that until I get my weight under control, my health will suffer.
I'm 5'8" and weigh on average 210lbs. My BMI isn't even morbidly obese, it is 31, which is just "regular" obese, but on top of that, a DEXA scan shows that I am actually only 25% body fat, with only 1lb of visceral fat.
Doctor's don't care about that, they see on the Epic chart that my BMI is > 30 and have to tell me some spiel about a healthier lifestyle so they check check off a checkbox and continue to the next screen.
> I'd consider 5'8 and 210lbs morbidly obese. An average male at 5'8 should generally weigh about 150lbs and no more than 164lbs
You would consider incorrectly then.
This person has ~155 pounds of lean body mass. 164 would put him at roughly a body builder level of fat, which basically requires a part time job in cooking and nutrition to maintain.
For reference, I’m in a similar situation to this person. I’m 5’11” (180cm) and about 200 lbs (91kg) with about 170 lbs of lean body mass. My dexa scan says that I’m 15% body fat, but I get the same lectures from doctors about being obese and needing a lifestyle change, all based on BMI and (I assume) my size (I’m barrel chested). It’s completely absurd.
Dexas are notoriously inaccurate. Your dexa scan is probably wrong, and you are fatter than you think. I've been lifting over a decade, so I have far more muscle mass than the average person, and I am 6'1", yet am still easily over 20% BF if I'm 200 lbs or more. Don't believe me? Try to get truly shredded. You'll see for yourself that you will have to lose far more weight than you think. Everyone is fatter and less muscular than they think they are, even if they're active. Unless of course you are a heavy steroid user, in which case you may actually be muscular enough for that to be valid. But for the average natural trainee? Nobody who's truly lean is getting an obese or morbidly obese BMI. Overweight at worst, maybe.
BMI is definitely inaccurate for those with greater amounts of muscle mass, but not as inaccurate as many would like to believe.
I didn’t want to belabor the point in my original post, but since you went there…
The next steps at the doctor is that I show them my MyFitnessPal nutrition tracking, my dexascan, and (at some point) take off my shirt. I ask them what exactly it is I should change. 100% of the time the answer has been something like “Oh, sorry. Please continue as you are doing.”
They just aren’t used to seeing muscular 200 pound dudes at my height in my area at my age (btw, I’m in my 50s).
Also, someone can workout in the gym all they want, but I think most people will struggle with lowering their body fat percentage if they don’t focus on their nutrition.
I realize that my lean body mass (both bones and muscle) are decreasing, and that rate of decrease be higher each year. That said, I’m doing what I can to maintain whatever muscle and bone mass I have.
Or that guy could be a burly bricklacker / concerete worker who can casually carry hundreds of pounds of weight all day every day in brutal conditions.
burly - maybe, but I haven't done any hard labor most of my life. I ran track as a kid, and kept my high metabolism - (RMR: 2460kcal, TDEE: 3380kcal); well lost it when my thyroid failed, but medicated myself back to it. I eat what I want, but its a very high lean-meat diet (lots of chicken breast and turkey because my wife likes them), but I don't limit my carb intake either, as I mostly burn sugar for energy (according to my Respiratory Exchange Ratio).
Somehow my body is just amazing at working without any help from me. I don't even exercise much. Maybe a few pushups a day, up and down my stairs at my house a couple dozen times a day, and probably 5-10k steps a day max.
Huh. The standard in your case is to measure waist circumference if BMI is high. Did no doctor do that? As long as you are below 40” or 37” if Asian you are considered good to go.
On top of that, I'm not sure if that is a real indication of anything, either.
The reason to do that is to get an idea of your abdominal fat (which is the more dangerous place for fat to store), but there are two types of abdominal fat, one is dangerous (visceral fat) and one is completely benign (subcutaneous fat). And a measurement around your waist won't tell you which you have.
I personally have almost all of my fat subcutaneous, with only 1lb of visceral fat (which is right in the perfect range).
Yes, humans have found that you don't need officially stamped statistics (and in many cases they're unreliable or "doctored" anyway), and that they can make general observations on their own, through something they call experience.
And a near universal experience with doctors for anybody paying attention is that.
One can reject it or accept it and improve upon it after checking its predictive power, or they can pause their thinking and wait for some authority to give them the official numbers on that.
I can't say literally all, but in my experience with having to get a new GP almost every year because of health insurance changes, location changes, hospital consolidation buying my GPs practice, and multiple doctors retiring or just quitting medicine (my last GP was tired of medicine after practicing for only 3 years). Over the last 20 years, I've had almost 15 GPs across 5 states (NY, NJ, CT, TX, LA). I also have multiple auto immune diseases, so I have had a handful of specialists of various flavors (endocrine, oncology - not for cancer, cardiology, and urology), but only need them occasionally.
Almost every single start of every single appointment (including a follow up from just a couple days prior), they comment about my BMI. It is the rare time they don't that I remember. My last urology appointment the doctor was very congenial, didn't even go over the lab work, just said, everything is looking good, asked how I was feeling, everything good, alright, refilled my prescriptions and left.
No. BMI does not work as a diagnostic measure for general population. The range of "normal" BMI values does depend at least on genetic lineage, gender and individual development history. Fine to compare two scandinavian lineage men, but if you compare e.g. a dutch man with an african woman oh boy, you error margins would be mid-to-high single digit units
> Waist to height ratio
Again, while not a bad metric per se, translates poorly between cohorts.
My understanding is that it doesnt even do that, because it creates false negatives for the so called skinny fat body type: significant visceral fat mass, which is what we are concerned about, but not much muscle or peripheral fat mass, thereby not being flagged by BMI screens, even though they are at risk.
An individual learns nothing from its calculation and it has no clinical value. I receive more constructive feedback from an auntie jabbing me in the chest and saying "you got fat".
> the great majority of people
There is wide morphological variety across human populations, so, no.
This underestimation has a name, "Normal Weight Obesity." Known by the slang "hot guy/girl fit" where the person looks like they would be physically fit because they're skinny but there's no muscle under there.
BMI works fine for people who aren't very muscular, which is the great majority of people. Waist to height ratio might be more informative for people with higher muscle mass.