BMI and how to calculate BMI? BMI It is a calculation used to estimate whether a person has a healthy body weight for their height. It is commonly used as a screening tool to assess whether an individual is underweight, at a healthy weight, overweight, or obese. The formula to calculate BMI is as follows:
BMI = weight (kg) / (height (m))^2
Here are the steps to calculate BMI:
Step 1: Measure your weight in kilograms (kg). If you have your weight in pounds (lbs), you can convert it to kilograms by dividing by 2.20462 (1 lb = 0.453592 kg).
Step 2: Measure your height in meters (m). If you have your height in feet and inches, you can convert it to meters by multiplying feet by 0.3048 (1 foot = 0.3048 m), and adding the inches converted to meters by multiplying by 0.0254 (1 inch = 0.0254 m). Then, square the height in meters.
Step 3: Use the formula to calculate BMI by dividing your weight in kilograms by the square of your height in meters.
For example, if you weigh 70 kg and your height is 1.75 m:
BMI = 70 kg / (1.75 m)^2 BMI = 70 kg / 3.06 m^2 BMI ≈ 22.9
The resulting number is your BMI. According to the World Health Organization (WHO), BMI categories are as follows:
- Underweight: BMI < 18.5
- Healthy weight: 18.5 ≤ BMI < 24.9
- Overweight: 25 ≤ BMI < 29.9
- Obese: BMI ≥ 30
Why cant we rely on BMI?
While BMI is a commonly used tool for assessing body weight and identifying potential weight-related health risks, it has some limitations and may not provide a complete and accurate assessment for everyone. Here are some reasons why BMI may not be solely relied upon:
Does not account for body composition:
BMI does not differentiate between muscle mass and body fat. Muscle weighs more than fat, so individuals with a higher muscle mass may have a higher BMI, even if they have a healthy level of body fat. On the other hand, older adults or individuals with certain health conditions may have a lower muscle mass and a lower BMI, even if they have excess body fat. This means that BMI may not accurately reflect an individual’s body composition.
Does not consider distribution of body fat:
BMI does not account for where fat is located in the body, which is important in determining health risks. Fat that is stored in the abdominal area (visceral fat) is associated with higher health risks compared to fat stored in other areas such as the hips and thighs (subcutaneous fat). Two individuals with the same BMI could have different levels of health risk depending on their distribution of body fat.
Does not consider other health factors:
BMI does not take into consideration other health factors such as blood pressure, cholesterol levels, blood sugar levels, or family history of diseases, which are important indicators of overall health. Some individuals with a normal BMI may still have other health risks due to other factors.
May not be applicable to all populations:
BMI was originally developed for and is most commonly applied to adults of European descent, and may not be as accurate for individuals from other ethnic groups. Different ethnicities may have different body compositions, bone densities, and health risks, which may not be accurately captured by BMI.
Does not consider individual differences:
Each person is unique, and factors such as age, gender, and fitness level can impact how BMI is interpreted. For example, BMI may not be as accurate for growing children and adolescents, pregnant women, or athletes with high muscle mass.
It’s important to remember that BMI is just one tool among many that can be used to assess health and weight status. It should not be relied upon solely, and a comprehensive assessment of an individual’s overall health, including factors beyond BMI, should be conducted by a healthcare professional to provide a more accurate and personalized evaluation.