Body Mass Index (BMI) is a simple screening tool that uses your height and weight to estimate body fat. While it's not a perfect measure, it's widely used by health professionals as a quick assessment.
BMI Categories
- **Under 18.5**: Underweight
- **18.5 - 24.9**: Normal weight
- **25.0 - 29.9**: Overweight
- **30.0 and above**: Obese
The Formula
**Metric**: BMI = weight(kg) / height(m)² **Imperial**: BMI = (weight(lbs) × 703) / height(in)²
Limitations of BMI
BMI doesn't distinguish between muscle and fat. This means:
- **Athletes** may have high BMI due to muscle mass, not body fat
- **Older adults** may have normal BMI but high body fat percentage
- **Pregnant women** should not use BMI as a health indicator
BMI also doesn't account for fat distribution, which matters for health risk. Visceral fat (around the waist) is more dangerous than subcutaneous fat.
Better Than BMI?
For a more complete picture, combine BMI with:
- **Waist circumference**: Risk increases above 40 inches (men) or 35 inches (women)
- **Body fat percentage**: Measured by calipers, bioimpedance, or DEXA scans
- **Waist-to-hip ratio**: A ratio above 0.9 (men) or 0.85 (women) indicates higher risk
What to Do With Your BMI
If your BMI is in the normal range, maintain your current lifestyle. If it's outside the normal range:
- **Underweight**: Consult a doctor about possible nutrient deficiencies
- **Overweight**: Focus on gradual weight loss through diet and exercise
- **Obese**: Work with a healthcare provider on a comprehensive weight management plan
Remember, BMI is a starting point, not a diagnosis. Always consult a healthcare provider for personalized advice.
Calculate your BMI with our BMI Calculator, then check your daily calorie needs with our Calorie Calculator.