Body Mass Index (BMI) is one of the most widely used health screening tools in the world — and one of the most misunderstood. A single number can't fully capture your health, but used correctly, BMI gives a useful starting point for understanding whether your weight is in a healthy range for your height.
BMI is calculated by dividing your weight by the square of your height:
Example: A person who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9 — well within the healthy range.
| BMI Range | Category | What it suggests |
|---|---|---|
| Below 18.5 | Underweight | May indicate malnutrition, eating disorder, or other health issues |
| 18.5 – 24.9 | ✅ Healthy weight | Generally associated with good health outcomes |
| 25.0 – 29.9 | Overweight | Increased risk of some health conditions |
| 30.0 – 34.9 | Obese (Class I) | Higher risk of heart disease, type 2 diabetes, hypertension |
| 35.0 – 39.9 | Obese (Class II) | Significantly elevated health risks |
| 40 and above | Severely Obese (Class III) | Very high risk; medical intervention often recommended |
BMI is a screening tool, not a diagnostic one. It has well-documented limitations you should be aware of:
Maintain your current lifestyle. Focus on consistent exercise, balanced nutrition, and regular check-ups. BMI doesn't need to be "optimised" — staying stable in the healthy range is the goal.
Small, sustainable changes make a big difference. A 5–10% reduction in body weight can significantly reduce the risk of type 2 diabetes and cardiovascular disease. Consult your GP before starting any significant diet or exercise programme.
Being underweight carries its own health risks including weakened immunity, bone density loss, and nutrient deficiencies. Speak with a healthcare provider to understand the underlying cause.