BMI Calculation and Classification for a Person 5'9" and 111 Pounds
A person who is 5'9" tall and weighs 111 pounds has a BMI of 16.4 kg/m², which classifies them as underweight according to established guidelines. 1
BMI Calculation
To calculate BMI, we use the following formula:
- BMI = weight (kg) / height (m)²
Converting the measurements:
- Height: 5'9" = 69 inches = 1.75 meters
- Weight: 111 pounds = 50.3 kg
Therefore:
- BMI = 50.3 kg / (1.75 m)² = 50.3 / 3.06 = 16.4 kg/m²
BMI Classification
According to the American Heart Association guidelines, BMI classifications for adults are as follows 1:
- Underweight: BMI < 18.5 kg/m²
- Normal or acceptable weight: BMI 18.5–24.9 kg/m²
- Overweight: BMI 25–29.9 kg/m²
- Obese: BMI ≥ 30 kg/m²
With a BMI of 16.4 kg/m², this person falls into the underweight category, as their BMI is below 18.5 kg/m².
Health Implications
Being underweight carries significant health risks that should not be overlooked:
- Increased risk of malnutrition
- Compromised immune function
- Potential hormonal imbalances
- Increased risk of osteoporosis and bone fractures
- Possible anemia and other nutritional deficiencies
- Reduced muscle mass and strength
Important Considerations
While BMI is a widely used screening tool, it has several limitations:
- BMI does not distinguish between fat mass and lean mass 2
- It doesn't account for body fat distribution, which is important for health risk assessment 3
- BMI may not be accurate for athletes with high muscle mass or elderly individuals with reduced muscle mass 4
For a more comprehensive assessment, additional measurements should be considered alongside BMI, such as:
- Waist circumference
- Body composition analysis
- Clinical evaluation for potential health complications related to being underweight
Clinical Significance
For a person with this BMI (16.4), clinical attention is warranted as being significantly underweight can lead to serious health consequences including compromised immunity, hormonal disruptions, and increased mortality risk in certain populations.