3 ms·

That’s an extreme example — he’s on the very lean side in terms of body fat %. A quick google search has him at ~10% body fat and 6’3” 236 lbs. That means his

by csa 6y ago

That’s an extreme example — he’s on the very lean side in terms of body fat %. A quick google search has him at ~10% body fat and 6’3” 236 lbs. That means his lean body mass is 212 lbs. So he could gain ~21 lbs and still be squarely in the average range of body fat (20%). Tack on 8-10 lbs more for the high end of average (24%). With the 20% number, his weight would be 257 —- that’s squarely in the BMI obese category for someone who is 6’3”. The BMI numbers are just not useful for folks with a relatively high amount of lean body mass for their height. One does not need to be a body builder or gym rat to meet this criterion. A small amount of body-weight exercises plus cardio is enough for people who build muscle easily (it’s not that rare). As others have said, BMI can be useful for measuring trends in populations, but some people get carried away when using it on individuals.

fortran77 6y ago
I don't think the average gym rat would have a BMI in the "obese" range (maybe overweight) unless they start getting into "Rock" territory. That was my point. I'm a "gym rat" (I'm the co-owner of a gym). Lift weights every day. I look athletic. I'm 5'10" 170#. That's a BMI of 24. Not even in the "overweight" range. Most people who say "BMI is meaningless/unfair/outdated" aren't in the group of people who outliers. It is a very good quick check, especially for considering the characteristics of a population when looking for correlations (like obesity vs cognitive ability, or obesity vs Type II diabetes). Doctors tend to record height and weight of patients with reasonable accuracy. Even doing other measurements like hip/waist ratio are a bit subjective (where, exactly is the waist. Where are the hips--especially on an obese subject. How "tight" are you holding the tape measure?) BMI eliminates those subjective elements.
- csa 6y ago
  > I'm 5'10" 170#. That's a BMI of 24. I’m 5’11” and 176#... of lean body mass per the last time I was in a dunk tank pre-covid. I am a desk jockey, I haven’t lifted a weight in over two decades, although I do cardio and body-weight exercises (push ups, pull ups, burpees, etc.). Needless to say, I’m an outlier while not being a gym rat, body builder, or construction worker. I don’t think people like me are rare enough such that concerns over BMI on an individual basis can or should be hand waved off. Every time I see a new doctor, they tell me I’m obese, I might be diabetic (my numbers are very normal), and how we might want to talk about that. I show them my dunk tank numbers, my myfitnesspal records of my diet, and my blood work, and they always just say “carry on”. I share this story to show that even medical professionals rely on BMI to an irresponsible level sometimes. I’m able to come prepared to the doctors because I understand the limits of BMI. I have several friends of similar build who have freaked out and sometimes made very stupid lifestyle changes (vastly undereating given their activity level) due to sloppy advice from doctors based on BMI. I’ve seen this cut the other way, too, with folks who have perfect looking BMIs but low lean body mass and are very unhealthy. I stand by my stance that BMI is good for measuring populations of people, but it’s a very crude tool on an individual basis. I hope my anecdote shows how this can happen even for a relatively normal person.

by csa 6y ago

fortran77 6y ago

I don't think the average gym rat would have a BMI in the "obese" range (maybe overweight) unless they start getting into "Rock" territory. That was my point. I'm a "gym rat" (I'm the co-owner of a gym). Lift weights every day. I look athletic. I'm 5'10" 170#. That's a BMI of 24. Not even in the "overweight" range. Most people who say "BMI is meaningless/unfair/outdated" aren't in the group of people who outliers. It is a very good quick check, especially for considering the characteristics of a population when looking for correlations (like obesity vs cognitive ability, or obesity vs Type II diabetes). Doctors tend to record height and weight of patients with reasonable accuracy. Even doing other measurements like hip/waist ratio are a bit subjective (where, exactly is the waist. Where are the hips--especially on an obese subject. How "tight" are you holding the tape measure?) BMI eliminates those subjective elements.

csa 6y ago
> I'm 5'10" 170#. That's a BMI of 24. I’m 5’11” and 176#... of lean body mass per the last time I was in a dunk tank pre-covid. I am a desk jockey, I haven’t lifted a weight in over two decades, although I do cardio and body-weight exercises (push ups, pull ups, burpees, etc.). Needless to say, I’m an outlier while not being a gym rat, body builder, or construction worker. I don’t think people like me are rare enough such that concerns over BMI on an individual basis can or should be hand waved off. Every time I see a new doctor, they tell me I’m obese, I might be diabetic (my numbers are very normal), and how we might want to talk about that. I show them my dunk tank numbers, my myfitnesspal records of my diet, and my blood work, and they always just say “carry on”. I share this story to show that even medical professionals rely on BMI to an irresponsible level sometimes. I’m able to come prepared to the doctors because I understand the limits of BMI. I have several friends of similar build who have freaked out and sometimes made very stupid lifestyle changes (vastly undereating given their activity level) due to sloppy advice from doctors based on BMI. I’ve seen this cut the other way, too, with folks who have perfect looking BMIs but low lean body mass and are very unhealthy. I stand by my stance that BMI is good for measuring populations of people, but it’s a very crude tool on an individual basis. I hope my anecdote shows how this can happen even for a relatively normal person.