why is BMI not a good indicator for health?


I have seen on several websites that BMI is not an accurate or reliable way of knowing if someone is healthy. Why is this information suddenly inaccurate?

In: Biology

Well your BMI is pretty much just how much fat you have on your outside relative to you body. I’m sure a healthy BMI more often than not means you’re doing ok though, at least compared to someone with a very high number.

However your organs can develop fat on them which isn’t good either. You could have high cholesterol, blood pressure, cancer, or any other number of diseases that have nothing to do with your BMI.

It only accounts for height and weight and not things like body fat. My friend weighs about 16 stone he is overweight but his brother in-law weighs 17 stone but he is in great health and looks great because his body fat percentage is very low and there is a LOT of muscle. The dude is a bodybuilder.

For everyday average people I think it’s a good guide to go off I think it does apply to most people as an average sort of chart of what is considered healthy and what isn’t.

Everyone’s body is different so you gotta go what how you feel after your workouts and stringent meal planning etc etc

One reason would be that someone who’s quite muscular and fit might still have a BMI that says they’re overweight. Muscle is heavier than fat.

It’s not “suddenly inaccurate”; there are better methods now.

BMI was NEVER a great method, but it was better than nothing.

The problem with it is that it doesn’t distinguish between fat and muscle, body water weight, bone density, and many other factors.

As a result, you could have an incredibly fit person with a BMI that shows them as being obese. I myself have had BMI results showing that I’m “morbidly obese”, but I’m clearly not. I work out a lot and have a higher muscle mass.

According to WHO , Health is a state of COMPLETE physical, mental and social well-being and not merely an absence of disease or infirmity.
BMI cannot cover all aspects of health. For example, BMI cannot tell if my blood sugar is going higher or not !

A lot of people are talking about calculators for bmi that only take into account height and weight. That is not all that accurate for the reasons they provided. It is an average, that can work for most people, but not everyone and we are all different.

It is worth noting that carrying around huge amounts of muscle mass is not inherently healthy either though. Stress from body building and carrying the weight of lots of muscle mass is not always good for your heart and bones/joints.

Hydrostatic Weighing to determine body fat percentage is actually very accurate and reliable as it does account for muscle. They basically float you in a giant special tank to see how that displaced weight compares to your dry weight and calculate how much of you is fat based in the difference.

BMI, for most people, IS a good indicator of health.
The vast vast majority of people don’t have enough muscle mass to really change their BMI significantly.
For 99.9% of people who have an extremely high BMI (over 40), it is a great indicator that they are/will have significant health issues.

The problem is that obesity isn’t a 1-to-1 indicator that someone has health problems at the moment. Just because someone is obese doesn’t mean that currently they are suffering. It’s just like smoking. Not all smokers have health issues, it just highly increases the chances.

There are obviously much more accurate indicators of health than just BMI, but because of its accessibility, it’s a great tool for health professionals.

BMI should be used as a starting point to check accurate health measurements. But in general, people with high BMI are at a increased risk for lots of diseases and it is a very good risk factor for them.

BMI is a very rough measure and doesn’t take account of other potential factors like muscle mass so BMI would count Arnold Schwarzenegger as obese. BMI is good for population studies where the other factors average out but it is really poor for individuals where those factors may be key.

BMI is very good at measuring populations, not so much at measuring individuals. But if the average BMI for, high school seniors (for example) increases nationwide, it almost definitely means they are fatter as a group.

BMI is also very easy to measure

BMI has never been a good indicator of health, nothing changed. It was originally created by a statistician who wanted to define what “average” was, and then used later by life insurance companies to try and determine who was “high risk” so they could charge us more. It wasn’t until the 70’s that its use became widespread thanks to a doctor named Ancel Keys who wanted to use it to promote diet pills.