BMI (Body Mass Index) is everywhere.
Doctors talk about it. Fitness apps calculate it for you.
Even social media influencers throw it into their “transformation” posts...
like it’s the ultimate health marker.
The truth is, BMI isn’t perfect, and it definitely doesn’t tell the whole story.
That doesn’t mean it’s useless.
It can give you a quick idea of how your weight stacks up relative to your height.
It’s simple, fast, and widely used, but it’s not designed to tell you everything about your health.
To understand its value and its limits you need to look a little deeper.
Let’s get into it.
What Is BMI, Really?
BMI is just a formula.
BMI = Weight (kg) / Height² (m²)
For example, if you weigh 70 kg and you’re 1.7 meters tall, your BMI comes out to 24.2.
According to the World Health Organization, that’s in the “normal weight” category.
Where Do You Land?
WHO defines BMI ranges like this:
|
Category |
BMI Range |
What It Means for Health |
|
Underweight |
Below 18.5 |
Malnutrition, weak immunity, brittle bones. |
|
Normal Weight |
18.5–24.9 |
Healthy range |
|
Overweight |
25–29.9 |
Higher risk of diabetes, heart strain, and joint pain. |
|
Obesity (Class I) |
30–34.9 |
Big jump in heart disease and metabolic issues. |
|
Obesity (Class II) |
35–39.9 |
Severe risks like organ damage and chronic conditions. |
|
Obesity (Class III) |
40 and above |
Life-threatening. |
The catch here is, BMI wasn’t designed for personal health. It was invented in the 1830s by Adolphe Quetelet, a mathematician studying something different.
Population trends….(not health)
The purpose of BMI is to give you a “general idea” on where you stand in the weight department,
but it’s not a precise way to find out if you’re healthy.
Let’s see why.
The Problem with BMI
BMI is not a diagnosis.
It tells you where you fall on a scale, but it doesn’t explain what’s actually happening in your body.
For starters,
- BMI can’t tell the difference between muscle and fat. A bodybuilder with low body fat might end up in the “overweight” category because muscle weighs more than fat.
- On the other side, someone with a “normal” BMI might carry unhealthy amounts of fat around their organs, which is way more dangerous than a “little extra padding” under the skin.
BMI also ignores other crucial factors like age, gender, and ethnicity.
As you age, you naturally lose muscle and gain fat, even if your weight stays the same.
Women generally carry more fat than men, and some ethnic groups like Indians are at higher risk for diabetes and heart disease at even lower BMI ranges. (J Gen Intern Med,2005)
When your BMI is outside the “normal” range, it can give you a hint about potential health risks.
But it’s not the number itself that’s harmful. It’s what’s happening inside your body.
Too low (under 18.5): Your body’s running on empty, and you get problems like low energy, weak immunity, fragile bones, and hormone imbalances.
Too high (30+): Extra fat stresses your heart, raises blood pressure, disrupts insulin, and fuels inflammation. These increase the risk of diabetes, heart disease, and even cancers.
It also impacts sleep. Fat around the throat can cause apnea, leaving you exhausted and straining your heart further.
Keeping the extremes aside, even being in the “normal” ranges may be misleading. Here’s why.
BMI doesn’t reveal “what” your weight is made of or “where” it’s stored,
Take someone with a BMI of 22.
It’s technically “normal”, but if they have low activity levels and a bad diet,
they may carry high visceral fat around their organs and little muscle mass,
It looks “thin” (which a lot of people equate with “fit”) on the outside but unhealthy inside.
If you want to understand the more about this, click here to read an advanced article on BMI.
What BMI Gets Right
BMI still has its place (even with some limitations we saw earlier).
It’s fast, easy, and can highlight trends that might be worth paying attention to.
If your BMI is in the overweight or obesity range, it’s a good reason to check in with your habits and health markers.
For a clearer picture, you need to dig deeper. Here are some tools.
What to Use Alongside BMI
Want the real story about your health? Pair BMI with these tools:
Waist-to-Hip Ratio: Measures where your fat sits. A higher ratio means more belly fat, a major risk for heart problems.
Body Composition Analysis: Breaks down fat vs. muscle vs. bone. Way more precise than BMI.
Blood Work & Biological Age: Check your cholesterol, blood sugar, and inflammation levels. These markers don’t lie.
And then, use our BioAge Calculator (Click Here) to find out your biological age.
BMI and Healthy Ageing.
Healthy ageing isn’t about chasing a perfect BMI.
It’s about building habits that keep your body working for you, not against you.
Start with food.
The less processed junk you eat, the better.
Stick to whole, nutrient-packed options. Lean protein, plenty of vegetables, healthy fats, and whole grains. .
Then, move your body regularly. You need both cardio and resistance training,
Cardio keeps your heart strong, and resistance training protects your muscles and bones.
Both are essential, especially as you age. Even a daily walk can make a big difference if you stay consistent.
Don’t overlook sleep and stress.
Poor sleep and chronic stress mess with your hormones, making weight management harder and increasing health risks.
Aim for 7–8 hours of quality sleep and find stress-busting techniques that work for you.
Click here to read how to get good sleep & a powerful technique to reduce stress quickly.
What Now?
BMI gives you a number to work with, but your health is so much more than a formula.
To get the full picture, you need to consider everything.
Fat distribution, muscle mass, blood markers, and even your habits.
The goal isn’t to hit a specific number. It’s to feel strong, energized, and capable of living your life the way you want to.
Because at the end of the day, health isn’t about a perfect BMI. It’s about making choices that keep you thriving.
And another good choice is joining our community at The Oak Age.
Think about it.. A group full of people like you, who are on a mission to make all their years count.
Oh and there are also some sweet benefits, like…
- Exclusive access to our biological age tool
- Challenges, and exclusive travel rewards to winners
- Easy, actionable healthy ageing tips
- Influence your circle and earn referral rewards
When you join us, you’re getting more than bare advice.
You’re stepping into an ecosystem designed to help you live better,
with practical benefits that actually make a difference.
