Body Mass Index (BMI)

Body Mass Index (BMI)

Body mass index (BMI) is a measurement tool to estimate the level of body fat. To calculate BMI, divide your weight (in kilograms) by the square of your height (in meters), where higher values suggest greater body fat. However, BMI alone should not be the sole parameter to evaluate your overall health and potential risks. Other assessments are also necessary.

BMI calculation

BMI =  $\frac{\mathrm{W}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}\mathrm{ }(\mathrm{i}\mathrm{n}\mathrm{ }\mathrm{k}\mathrm{i}\mathrm{l}\mathrm{o}\mathrm{g}\mathrm{r}\mathrm{a}\mathrm{m}\mathrm{s})}{{\mathrm{H}\mathrm{e}\mathrm{i}\mathrm{g}\mathrm{h}\mathrm{t}}^2(\mathrm{i}\mathrm{n}\mathrm{ }\mathrm{m}\mathrm{e}\mathrm{t}\mathrm{e}\mathrm{r}\mathrm{s})}$

For example: If your height is 156 centimeters and your weight is 45 kilograms, your BMI is 18.5. kg/m2

BMI 18.5 = $\frac{45}{1.56 \mathrm{x}\mathrm{ }1.56}$

Weight classification with BMI

Having excess body fat can contribute to various health problems, including heart disease, stroke, and Type 2 diabetes, while having insufficient body fat may indicate malnutrition and its associated complications. Maintaining appropriate body fat is essential because it is a necessary energy reserve and protective layer for internal organs. Body fat can help regulate body temperature and help store fat-soluble vitamins, including vitamins A, D, and E. 

Besides BMI, you should also consider other measurement parameters:

• Waist circumference.
• Skinfold thicknesses, such as over-the-shoulder blades or the back of your upper arms, are measured with a skinfold caliper.
• Air Displacement Plethysmography (ADP) and Dual-Energy X-Ray Absorptiometry (DEXA)

For children's and teenagers' BMI, you should consult a doctor for optimal weight and height based on their age.

Health risk screening with BMI

People with BMI below 18.5 (underweight) are at higher risk of developing malnutrition, anemia, osteoporosis, infertility, and weakened immunity with frequent infections. Additional blood tests can confirm if malnutrition is present.

People with higher BMI (overweight or obese) have an increased risk of Type 2 diabetes, heart disease, hypertension, gallstones, osteoarthritis, sleep apnea, depression, mental health problems, and cancers in the breast, colon, endometrial, and gallbladder. Your doctor may order lipid panels or a comprehensive metabolic panel if your BMI is high.

Some people with a high BMI may not have those health conditions, whereas some with a normal BMI may develop a health condition. Body fat is not the only determining factor; other factors playing an important role are genes, family history, and lifestyle.

Limitations of BMI

BMI is a quick and easy tool to assess your estimated body fat. However, there are limitations as follows:

• BMI cannot differentiate lean body mass from fat mass. Some people can have a high BMI because they are very muscular.
• BMI is not an appropriate tool to determine the body fat of children, teenagers, pregnant women, athletes, bodybuilders, seniors aged 65 and older, or people with muscle atrophy.
• BMI cannot identify the location or distribution of body fat. Excessive fat in the abdomen can be associated with an increased risk of health issues.

Considering these limitations, one should combine BMI with other assessment factors, such as lifestyle and family history. Consult your doctor to obtain a comprehensive and proper evaluation of your health status and potential risks.