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Is Body Mass Index A Reliable Indicator

    The body stores energy as fat. However, when you fall sick, you may see an increase in body fat. This mainly depends on where the body stores fat. The fat stored by your body is measured with the help of a dual-energy absorptiometry, also known as a DXA machine. You can have a DXA scan or choose to calculate your body mass index (BMI) if you are looking to figure out the fat stored by your body. But is BMI a reliable indicator? At the population level, BMI is a reliable indicator of overall health. However, how the fat on your body is distributed is more important than the amount of fat. This is especially true when trying to assess the risk of disease. Hence, you’ll find that many doctors say that waist circumference is a better indicator of health than BMI. Abdominal obesity has been linked to higher chances of getting cardiovascular disease, type 2 diabetes, and cancer.

    What is BMI?

    BMI- body mass index- is used to measure your weight to ensure the best health. All you have to do is divide your weight in kilograms by your height in meters squared to figure out your BMI.

    It must be kept in mind that BMI only applies to adults. This is because children and adolescents continue to grow every week. Hence, set BMI cut-offs for smaller age groups are not accurate. As soon as a person enters adulthood, the rise in BMI is because of a higher body fat percentage.

    The BMI calculator can be used by adults who are aware of the following:

      • Their weight in kilograms (kg)
      • Their height in centimeters (cm)

    The World Health Organization has set a standard to help individuals identify as underweight, overweight, obese, or healthy. Here is how they do this:

      • Those under 18.5 kg/m2 are considered to be underweight and malnourished.
      • Those who range from 18.5 to 24.9 kg/m2 are considered to be healthy young adults.
      • Those who range from 25.0 to 29.9 kg/m2 are considered to be overweight.
      • Those over 30 kg/m2 are considered to be obese.

    BMI Is Not a Reliable Indicator

    Usually, BMI is used for signaling risk for morbidity and mortality. This means a risk of disease and death.

    Even though BMI is used to calculate the percentage of body fat of adults of the same age and sex, the BMI figure should not always be considered reliable. BMI can overestimate the amount of body fat in:

      • Bodybuilders
      • Athletes
      • Pregnant women

    BMI can underestimate the body fat in:

      • Older adults, usually the elderly
      • Those who have a physical disability. This includes individuals who have muscle wasting or cannot walk properly.

    BMI also does not provide an accurate reading for:

      • Individuals going through eating disorders, such as anorexia nervosa
      • Obesity caused by disease

    Why BMI Cannot Be Trusted

    The general rules state that individuals who have a higher body fat are more at risk for diseases. However, BMI readings cannot tell the difference between muscle mass and body fat. Here’s how:


    Bodybuilders do not usually use BMI to determine body fat because their BMI will always be high, regardless of how fit they are. This is due to the muscle bulk that their body holds, not because they are overweight.

    Physical Disabilities

    Individuals who cannot walk or have a physical disability may experience muscle wasting. Even though their BMI reading may be on the lower side, it does not mean that they are underweight. To ensure that such individuals are healthy and remain free of disease, consult a dietitian.


    BMI is calculated based on an individual’s height. However, the readings tend to be incorrect for shorter than average and taller than ordinary people. Hence, BMI should be disregarded amongst adults who are less than 150 cm and taller than 190 cm.


    Did you know that your ethnicity has an impact on the BMI reading? Asians and Indians have always been known to have a higher body mass index as compared to Europeans. Hence, the set standard for underweight and overweight is different for these populations.

    In Asian populations, the chances of diabetes and cardiovascular disease start when the BMI readings fall as low as 23 kg/m2. Other populations around the world have similar risks of disease but at a higher BMI. This includes those of Maori origin and the people of Torres Strait Islander.

    Why Waist Circumference is a Better Indicator of Health

    Rather than relying on BMI, an individual’s waist circumference can be looked at when predicting the risk of diseases. As an adult, you should merge your BMI reading with your waist circumference to determine an accurate measurement and ensure that you are not high at risk for contracting diseases.

    Some people also have some weight around their abdomen, commonly referred to as a “potbelly.” Regardless of your weight or body size, this is not considered healthy and puts one at risk for obesity-related illnesses. However, fat that deposits itself around the hips is not considered to be a huge risk. Men are more likely to get fat around their waist, putting them at high risk for obesity.

    According to research, the way the body fat is distributed affects the risk of diabetes, hypertension, high cholesterol, and cardiovascular diseases.

    Here is how health risks and body fat distribution are categorized:

      • Those with a slim waist are at least risk as their body fat is evenly distributed.
      • Those who are overweight but do not have a pot belly are at moderate risk.
      • Those who are slim overall and do not have a pot belly are at moderate to high risk.
      • Those who are overweight and have extra belly fat are considered to be at high risk.

    When dealing with weight issues, it is best to consult a doctor or dietitian who can guide you correctly and help you make lifestyle changes. Remember to eat healthily and include moderate levels of exercise into your daily routine, regardless of your age.