Body Mass Index (BMI)

Body Mass Index (BMI) is a simple and widely used metric to assess an individual’s body weight in relation to their height. It provides an approximate measure of whether a person falls within a healthy weight range, making it a valuable tool for identifying potential weight-related health risks. BMI is calculated by dividing a person’s weight in kilograms by the square of their height in meters (kg/m²).

While easy to use, BMI has its limitations as it doesn’t account for variations in muscle mass, bone density, or fat distribution, making it most effective when combined with other health assessments.

Body mass index (BMI): what is it?

A medical evaluation technique called the body mass index, or BMI determines your body fat percentage by dividing your height by your weight. Physicians/Doctors check BMI by dividing height in meters squared (m2) by weight in kilograms (kg).

While BMI is a good indicator of body fat (the higher the number, the more body fat you may have), it isn’t always accurate. Health cannot be diagnosed by BMI alone. In addition to other tools and testing, healthcare providers use a patient’s BMI to assess their health and risks.

Type 2 diabetes, heart disease, and stroke can all be brought on by having too much body fat. A decreased body fat percentage might be a sign of malnourished. The right amount of body fat makes it easier for vitamins and minerals to be absorbed. Additionally, it protects your organs, helps regulate body temperature, and gives your body a source of energy.

It is not proper to assess a youngster or teen’s weight using the conventional BMI chart. Please talk about the appropriate weight range for your child’s height and age with their physician.

What is the purpose of BMI?

BMI is a metric used by medical practitioners to help determine weight types and as a screening tool for certain medical conditions.

Using BMI to Diagnose Weight Types:

• Underweight: Less than 18.5.
• Optimum range: 18.5 to 24.9.
• Overweight: 25 to 29.9.
• Class I obesity: 30 to 34.9.
• Class II obesity: 35 to 39.9.
• Class III obesity: More than 40.

To Calculate BMI Click Here

Providers categorize weight types using a variety of methods besides BMI. Other resources consist of:

calculating the circumference of the waist.
For example, use skinfold calipers to determine the firmness of the skin underneath your shoulder blades and at the backside of your upper arms.

The use of DEXA scans and atmospheric displacement plethysmography (ADP) is less common.

Using BMI to screen for health concerns

If your body mass index is less than 18.5 (underweight), you may be more vulnerable to the following issues:

• malnourishment.
• anaemia.
• compromised immune system, which might lead to an increase in infections and illnesses.
• osteoporosis.
• infertility.

Your medical professional may likely do certain blood tests and other tests if you are underweight to evaluate your overall health and establish whether you are malnourished.

Generally speaking, a higher BMI raises your chance of getting the following illnesses:

• heart condition.
• High blood pressure.
• Type 2 diabetes.
• gallstones.
• osteoarthritis.
• Sleep Apnoea.
• several types of cancer, such as gallbladder, endometrial, breast, and colon cancer.
• depression as well as additional mental health issues.

Remember that you can have any of the diseases listed above and still have a low body mass index. A high BMI can also exist without any of these problems. These disorders are mostly influenced by genetics as well as other factors, such as cigarette smoking.

Your doctor will probably prescribe specific blood tests, including a lipid panel and a comprehensive metabolic panel, to assess your overall health if your BMI indicates that you may be obese.

Adult Body Mass Index

The following standard weight status categories can be used by adults aged 20 and up to interpret their BMI. For both men and women, regardless of age or body shape, these are the same:

BMI	Weight Status
Below 18.5	Underweight
18.5 – 24.9	Normal
25.0 – 29.9	Overweight
30.0 and above	Obese

Children’s Body Mass Index

People under 20 have a varied interpretation of BMI. The consequences for children and adolescents might differ according to age and gender, even though the same method is used to calculate BMI for all age groups. The general population’s body fat percentage discount fluctuates with maturity. Young boys and girls experience it differently as well. Girls tend to acquire body fat at an earlier age and in greater quantities than guys.

The CDC displays BMI for kids and teenagers as a percentile rating using age growth chartsTrusted Source. A child’s BMI with other kids their age and gender is shown by each percentile. Children would be considered obese, for example, if their BMI was at or above the 95th percentile. This means that they have a greater proportion of body fat than 95% of children in the same age and gender group.

Percentile Weight Status

BMI	Weight Status
Below 5th	Underweight
5th to 85th	Normal or healthy weight
85th to 95th	Overweight
95th and above	Obese

How is my BMI determined?

These techniques can help you calculate your personal BMI:

Some of you may multiply your weight in pounds by 703 by that number.
One foot is equal to twelve inches, therefore divide that response by your height in inches.
This time, break down the response by your height in inches.
For example, a person who weighs 180 pounds and is 5 feet 5 inches tall (65 inches overall) may have their BMI calculated using the following formula:

• 180 x 703 = 126,540.
• 126,540 / 65 = 1,946.769.
• 1,946.769 / 65 = 29.95.
• Their BMI would be 29.9.

What BMI is considered healthy?

Healthy BMI – 18.5 and 24.9.

It is crucial to keep in mind that other factors influence general health besides body fatness. Your general health and your risk of contracting specific medical diseases are influenced by several additional factors, including your genetic makeup, level of exercise, use of tobacco products, alcohol consumption, smoking cigarettes, and mental health issues.

What are BMI’s limitations?

There are several drawbacks to the typical BMI chart. Avoiding placing too much emphasis on your BMI is therefore essential.

Healthcare professionals continue to use the BMI chart because it’s the most rapid way to determine an individual’s estimated body fat percentage, even though it may not be correct for certain people.

Limitations of diagnosing weight types with BMI

When it comes to identifying weight kinds, the conventional BMI has limitations, such as:

Lean body mass, or the weight of everything in your body other than fat, and fat mass are not distinguished by BMI. As a consequence of this, individuals may have a high BMI and be powerful nevertheless they could additionally have a fairly small amount of muscle mass, and vice versa.
Although persons assigned female at birth (AFAB) often have greater body fat than those designated male at birth (AMAB), both groups use the same BMI chart.
The rising average adult height over time has not been accounted for in the BMI figure.

The typical BMI chart should not be used to determine the body fat percentage in the following groups:

• Bodybuilders and athletes.
• kids and teens.
• pregnant individuals.
• those who are older than 65.
• those who suffer from medical problems that cause muscular atrophy, or wasting.

The drawbacks of using BMI as a health condition screening method

There are significant drawbacks to using the BMI as a screening tool to determine a person’s risk of developing specific diseases, such as heart disease and Type 2 diabetes. These include:

The BMI of an individual does not account for the arrangement and position of body fat. This is a problem since accumulating excess fat in some parts of your body, like your abdomen, is linked to a higher risk of developing certain illnesses than accumulating too much fat in other areas of your body, such as your legs.

Factors including familial length (average lifespan), family history of diabetes, high blood pressure, cardiovascular disease, and high cholesterol (dyslipidemia), as well as family history of cancer, are sometimes overlooked in the association between BMI and mortality rate.

Summary

In addition to aiding in demographic and trend studies, BMI may offer a broad indicator of a person’s weight and health. It is arguably the finest guide we currently have.

To avoid acquiring too much weight in the first place, it could be more crucial to maintain a healthy lifestyle that includes regular exercise and a balanced diet.

FAQs

References

• Professional, C. C. M. (2024c, October 28). Body Mass Index (BMI). Cleveland Clinic. https://my.clevelandclinic.org/health/articles/9464-body-mass-index-bmi
• Shmerling, R. H., MD. (2023, May 5). How useful is the body mass index (BMI)? Harvard Health. https://www.health.harvard.edu/blog/how-useful-is-the-body-mass-index-bmi-201603309339
• Body mass index: MedlinePlus Medical Encyclopedia. (n.d.). https://medlineplus.gov/ency/article/007196.htm
• Brazier, Y. (2023, July 26). What are the limitations of BMI? https://www.medicalnewstoday.com/articles/323543
• McCarthy, M. (2021, May 10). Experts Say BMI Measurements Are a Starting Point, Not a Goal. Healthline. https://www.healthline.com/health-news/experts-say-bmi-measurements-are-a-starting-point-not-a-goal
• Thakkar, D. (2023a, December 13). Body Mass Index (BMI) – What It Is, How to Calculate It. Mobile Physiotherapy Clinic. https://mobilephysiotherapyclinic.in/body-mass-index-bmi/