What is BMI?
Body Mass Index (BMI) is a simple yet powerful tool that uses your height and weight to estimate whether your weight is within a healthy range. It is calculated by dividing your weight in kilograms by the square of your height in meters.
Formula:
BMI = Weight (kg) / [Height (m)]²
BMI helps screen for potential weight-related health risks, but it does not directly measure body fat or overall health. Factors like muscle mass, bone density, and body composition also influence your true health status, so BMI should be considered alongside other health assessments.
Why Is BMI Checked During Health Visits?
Whenever you visit a healthcare professional, vital parameters such as weight, height, and blood pressure are recorded. These values can be used to determine your Body Mass Index (BMI) — a quick way to understand whether your body weight is within a healthy range.
Maintaining a healthy BMI offers numerous benefits, including:
- • Reduced joint and muscle pain
- • Higher energy levels
- • Balanced blood pressure
- • Lower strain on the heart and circulatory system
- • Improved sleep quality
- • Reduced triglycerides and blood sugar levels
- • Lower risk of chronic lifestyle diseases
Standard BMI Chart for Adults (as per WHO & Asia-Pacific Guidelines)
Asia-Pacific Classification (Applicable for Indians):
| Category |
BMI Range (kg/m²) |
| Underweight |
Less than 18.5 |
| Normal |
18.5 – 22.9 |
| Overweight |
23 – 24.9 |
| Obese |
25 and above |
WHO Global Classification:
| Category |
BMI Range (kg/m²) |
| Underweight |
<18.5 |
| Normal |
18.5 – 24.9 |
| Pre-Obesity |
25.0 – 29.9 |
| Obesity Class I |
30.0 – 34.9 |
| Obesity Class II |
35.0 – 39.9 |
| Obesity Class III |
≥40 |
Note: BMI is not a diagnostic tool. Always consider other health indicators like muscle mass, fat distribution, and metabolic markers. Consult a healthcare provider for personalized guidance
Health Risks Associated with Different BMI Ranges
1. Underweight (BMI <18.5)< /p>
Being underweight indicates insufficient nutrient intake, which can:
- • Weaken immunity and slow recovery from illness
- • Increase infection risk
- • Cause fatigue, dehydration, and malnutrition
- • Reduce bone density and fertility
- • Increase surgical or medical complications
If you are underweight, seek advice from a qualified nutritionist or dietitian to identify the root cause and follow a personalized weight gain diet plan. In some cases, mass gainers can help build lean muscle mass — but always check the product’s nutritional profile before use.
2. Overweight & Obese (BMI >23)
Carrying excess weight can affect nearly every system in the body, including your heart, lungs, hormones, and mental health.
Common health risks include:
-
• Cardiovascular diseases
- • Type 2 diabetes
- • Fatty liver and gallbladder issues
- • Joint and mobility problems
- • Sleep apnea
- • Hormonal and reproductive disorders
- • Mental health challenges like anxiety and depression
Working with a nutritionist or healthcare professional can help you adopt lifestyle changes such as balanced eating, physical activity, and stress management to maintain a healthy weight.
How to Calculate BMI
Here’s how you can easily calculate your BMI manually or using a BMI calculator tool:
1. Measure your weight in kilograms (kg).
o To convert pounds (lbs) to kilograms: divide weight by 2.205.
2. Measure your height in meters (m).
o To convert inches to meters: divide height in inches by 39.37.
3. Square your height in meters:
Example: If height = 1.7 m → 1.7 × 1.7 = 2.89
4. Divide your weight by your squared height:
Example: If weight = 70 kg → 70 ÷ 2.89 = 24.2 BMI
Limitations of BMI
While BMI is a helpful screening tool, it has its limitations:
- • It doesn’t differentiate between muscle and fat mass (e.g., athletes may appear “overweight”).
- • It doesn’t indicate fat distribution (visceral fat is more harmful than subcutaneous fat).
- • It’s not suitable for children, pregnant women, or athletes with high muscle mass
Hence, BMI should be complemented with additional assessments such as waist circumference, skinfold thickness, and body composition analysis for a complete health evaluation.
How to Maintain a Healthy BMI
While BMI is a helpful screening tool, it has its limitations:
If your BMI falls outside the normal range, small lifestyle changes can help restore balance and promote long-term health.
Here are some practical steps to manage your BMI:
- ✅ Engage in regular physical activity (at least 150 minutes per week)
- ✅ Eat a balanced, nutrient-rich diet with whole grains, lean protein, and vegetables
- ✅ Stay hydrated throughout the day
- ✅ Avoid skipping meals
- ✅ Limit alcohol, processed, and sugary foods
- ✅ Get adequate sleep and manage stress
Key Takeaway
Your Body Mass Index (BMI) is a quick and simple indicator to understand whether your weight aligns with your height. While it offers valuable insights, it should not be the sole indicator of health. For a comprehensive evaluation, consider other parameters like waist-to-hip ratio, body fat percentage, and metabolic health.
Maintaining a healthy BMI through proper nutrition, physical activity, and lifestyle choices can significantly reduce your risk of chronic diseases and promote long-term wellness. Always consult a certified healthcare provider or nutrition expert for personalized guidance.
