Recently, in social media feeds and gym check-in groups, more and more people are posting their BMI. You know, it looks quite scientific at first glance—once the number comes out, it seems to set a tone of 'good' or 'bad' for your body. But let me tell you, I've looked through those screenshots people post, and at least half of them have calculated the number incorrectly.
What's going on? It's not that they're deliberately faking it; they simply don't understand what BMI is for. BMI is calculated by taking your weight in kilograms and dividing it by the square of your height in meters. Simple formula, right? But look at how they do it: some use 'jin' (a Chinese unit equal to half a kilogram) as if it were kilograms and divide directly by height—how could that be right? Some report their height measured with shoes on, adding an extra five centimeters, which creates a significant error. Even worse, some people post a BMI of 22.3, which looks great, but when asked, it turns out that was from their physical exam last year. This year they've gained ten jin, yet they're still using old data to seek validation.
Then there's another group that's truly misled by BMI. Take those muscular guys at the gym with body fat so low it's like a washboard—their BMI might be 25 or even 27, which by standard is 'overweight.' Then they come to you and say, 'Oh, my BMI is unhealthy,' and you believe that? With that physique, their biological age is ten years younger than their actual age—how is that unhealthy? Conversely, those sedentary girls with light weight might have a BMI below 18.5, which looks 'underweight' but seems normal, yet when you pinch their waist, it's all soft flesh, and their visceral fat might even be excessive. BMI only looks at weight and height; it can't tell whether that weight is muscle or fat, nor can it see where fat is stored.
So I say, half of those posting BMI check-ins at the gym have miscalculated, and the other half are intimidated by the number. Who actually looks at BMI among real fitness enthusiasts? They look at body fat percentage, waist-to-hip ratio, and changes in measurements. Have you ever seen a bodybuilder posting BMI daily? For them, that number is a joke.
So, is BMI still useful? Yes, but it's for the general public—it's an entry-level indicator for health screening, not a verdict that defines you. If your BMI is in the normal range (18.5-23.9), it means your weight isn't a major issue. But if your BMI is normal yet you always feel out of shape or weak, what you should focus on is muscle mass and posture, not obsessing over the digits after the decimal point. If your BMI is high, don't panic right away; first think about whether you're the 'sturdy' type who lifts weights daily or the 'soft and puffy' type who sits all day without moving.
Remember, any single indicator is one-sided. Instead of posting BMI check-ins, why not post how much you squat, how many kilometers you can run, or how many centimeters your waist has shrunk? That number is something you've earned yourself. As for BMI, if you calculate it correctly, just use it as a reference. If you get it wrong, don't bring it out to embarrass yourself, lest those in the know laugh at you silently.
Next time you're at the gym and see someone making a fuss about BMI, just smile and ask them, 'Bro, did you calculate that number using kilograms or jin?' I guarantee they'll be stunned.