⚖️ Your BMI is a Starting Point, Not a Verdict
Body Mass Index (BMI) divides your weight in kilograms by the square of your height in metres. It is fast, free, and requires no equipment — which is why doctors have used it as a population-level screening tool since the 1970s.
But it was never designed to diagnose individual health. Here is what you need to know.
**What BMI tells you**
A BMI below 18.5 is classified as underweight; 18.5–24.9 as healthy range; 25–29.9 as overweight; and 30+ as obese. These thresholds correlate with increased risk of cardiovascular disease, type 2 diabetes, and joint problems at the population level.
**What BMI misses**
- A powerlifter with 10% body fat can have a BMI of 30 and excellent metabolic health.
- A sedentary person at BMI 22 can carry dangerous visceral fat around internal organs.
- Bone density, muscle mass, fluid retention, and fat distribution are invisible to BMI.
- The thresholds were derived from studies of white European populations and may not translate accurately to people of Asian, African, or other heritage.
**Better markers to track alongside BMI**
Waist circumference (below 94 cm for men, 80 cm for women is generally lower risk), resting heart rate, blood pressure, fasting blood sugar, and how you feel climbing a flight of stairs are all more informative than a single number.
**How Lunahealth uses BMI**
We use your BMI category to tune the intensity of exercise suggestions and calorie targets. If your BMI is at either extreme, we flag it and suggest consulting a professional — because personalised guidance matters more than any formula.
The goal is not to be a "correct" number. The goal is to feel capable, energised, and well.