Body Mass Index
Body Mass Index (BMI) is a widely used tool for assessing body weight relative to height. It is calculated by dividing a person’s weight by the square of their height. Clinically, BMI is a quick and accessible measure to categorize weight ranges. This makes it valuable for identifying weight-related health risks, as higher BMI values are associated with conditions like cardiovascular disease, diabetes, and certain cancers.
BMI Categories
Underweight: BMI < 18.5
Normal weight: BMI 18.5–24.9
Overweight: BMI 25–29.9
Obesity:
-Class 1 Obesity: BMI 30–34.9
-Class 2 Obesity: BMI 35–39.9
-Class 3 Obesity: BMI ≥ 40
Other Body Composition Metrics and Diagnostics
Waist Circumference
Measuring waist circumference provides insight into abdominal fat, which is strongly linked to metabolic health risks. While easy and cost-effective, it doesn’t capture overall body composition or fat-to-muscle ratio.
Waist-to-Hip Ratio (WHR)
WHR calculates the distribution of fat between the waist and hips, helping assess cardiovascular and metabolic risks. It’s more informative than BMI for central obesity but lacks precision for total body fat or muscle mass.
Body Fat Percentage
Body fat percentage measures the proportion of fat mass to total body weight. Methods like bioelectrical impedance analysis (BIA), skinfold calipers, and Dual-Energy X-ray Absorptiometry (DEXA) scans can estimate this. BIA and calipers are quick and accessible but can be less accurate. DEXA, considered the gold standard, provides detailed information on body fat and lean mass but can be costly and requires specialized equipment.
Bioelectrical Impedance Analysis (BIA)
BIA devices send a harmless electrical current through the body, estimating body fat percentage and lean mass. While affordable and easy to use, accuracy can be affected by factors like hydration level and meal timing.
Dual-Energy X-ray Absorptiometry (DEXA) Scans
DEXA scans provide a comprehensive analysis of body fat, muscle mass, and bone density. While highly accurate, DEXA requires medical facilities, is more expensive, and exposes individuals to minimal radiation.