Body Mass Index

Discover the Key to Health and Well-being: Understanding Body Mass Index. Learn how Body Mass Index is calculated and why it is an important indicator of health.

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Why Is Your BMI Important?


Your Body Mass Index (BMI) is a simple tool that compares your weight to your height to give you an idea of whether you’re underweight, at a healthy weight, overweight, or obese. While it’s not a perfect measurement, it’s an important starting point for understanding your overall health and fitness.

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What is BMI

What is BMI?

BMI (Body Mass Index) measures body leanness or corpulence based on height and weight. It's a general indicator of whether a person has a healthy weight for their height.

BMI Classification for Adults
Classification BMI range (kg/m²)
Severe Thinness < 16
Moderate Thinness 16 - 17
Mild Thinness 17 - 18.5
Normal 18.5 - 25
Overweight 25 - 30
Obese Class I 30 - 35
Obese Class II 35 - 40
Obese Class III > 40
BMI for Children and Teens (Ages 2–20)
Category Percentile Range
Underweight < 5%
Healthy weight 5% - 85%
At risk of overweight 85% - 95%
Overweight > 95%
Risks of Being Overweight
  • High blood pressure, Type II diabetes, coronary heart disease
  • Osteoarthritis, sleep apnea, certain cancers
  • Lower quality of life, depression, increased risk of mortality
Risks of Being Underweight
  • Malnutrition, osteoporosis, lowered immune function
  • Growth/development issues, reproductive problems, surgery risks
  • Possible underlying medical conditions
Limitations of BMI

BMI does not account for muscle mass, fat distribution, age, or gender. It may misclassify muscular individuals or misestimate fat in seniors or children.

BMI Formulas
  • US Units: BMI = 703 × weight (lbs) / height² (in)
  • Metric Units: BMI = weight (kg) / height² (m)

Example: A person 5'10" and 160 lbs has a BMI of 23.0

BMI Prime

BMI Prime = BMI / 25

Used to assess how far someone is from the healthy upper limit. A value above 1 indicates overweight; below 0.74 indicates underweight.

Ponderal Index

Similar to BMI, but height is cubed. It’s more accurate for very tall or very short individuals.

  • US Units: PI = height (in) / ∛weight (lbs)
  • Metric Units: PI = weight (kg) / height³ (m)

Determine Your Body Mass Index

Calculate Your BMI

BMI Calculator

 

Body Gang BMI Calculator


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Let Us Help

BMI doesn’t measure body fat directly, and it doesn’t take into account muscle mass. That means athletes and people with higher muscle mass may have a “high BMI” even if they’re very healthy.

That’s why at Body Gang Fitness, we use BMI as just one piece of the puzzle—along with body composition, nutrition, and lifestyle habits—to give you the full picture of your health. Book a FREE Consultation

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