Understanding BMI: Complete Guide to Body Mass Index

What is BMI?

BMI (Body Mass Index) is a measure of body fat based on height and weight. It's used to categorize underweight, normal weight, overweight, and obesity.

BMI Formula

Or in pounds and inches: BMI = (Weight in lbs × 703) / (Height in inches)²

BMI Categories (WHO Classification)

Category	BMI Range
Severe Underweight	< 16.0
Moderate Underweight	16.0 - 16.9
Mild Underweight	17.0 - 18.4
Normal Weight	18.5 - 24.9
Overweight	25.0 - 29.9
Obese Class I	30.0 - 34.9
Obese Class II	35.0 - 39.9
Obese Class III	≥ 40.0

Example Calculations

Example 1: Person weighing 70kg, height 1.75m

BMI = 70 / (1.75 × 1.75) = 70 / 3.06 = 22.9 (Normal Weight)

Example 2: Person weighing 85kg, height 1.65m

BMI = 85 / (1.65 × 1.65) = 85 / 2.72 = 31.2 (Obese Class I)

Limitations of BMI

BMI doesn't account for:

• Muscle mass (athletes may show overweight)
• Age (older adults have more fat)
• Gender (women have more body fat)
• Body frame size
• Fat distribution

Ideal Weight Range (For given height)

For height 5'5" (165 cm): Ideal weight = 50-68 kg (BMI 18.5-24.9)

For height 5'9" (175 cm): Ideal weight = 57-77 kg

Tips to Achieve Healthy BMI

If Underweight:

• Increase calorie intake with nutritious foods
• Add protein-rich foods (eggs, dairy, legumes)
• Strength training to build muscle

If Overweight/Obese:

• Calorie deficit (burn more than you eat)
• Regular cardio exercise (walking, running, cycling)
• Reduce processed foods and sugar
• Drink plenty of water
• Get adequate sleep (7-8 hours)

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