BMI stands for body mass index and is used to measure body fat based on a person’s weight in relation to his or her height. But it doesn’t measure body fat directly. Instead, BMI uses an equation to make an approximation.
This tool helps determine whether a person is underweight, overweight or has a healthy weight for their height. A high BMI can be a sign of too much fat on the body, while a low BMI can be a sign of too little fat.
The higher a person’s BMI, the greater the risk of developing certain serious conditions, such as heart disease, high blood pressure and diabetes.
A very low BMI is also not healthy, as it can put a person at a higher risk of health problems like bone loss, decreased immune function and anemia.
BMI is applicable to most adult men and women age 20 and over. For children age 2 and over, a BMI percentile comparing a child’s results to that of other children of the same age and sex can be used to assess a child’s weight status.
To calculate your BMI, you do not need any equipment or a visit to your doctor. You can find several online BMI calculators. All you need to do is enter your height in feet and inches and weight in pounds, and you will see your calculated BMI. to calculate your BMI as per the National Institute for Health.
Here are the BMI ranges and weight statuses for adults age 20 and older. The data is the same for men and women of all ages and body types.
The Centers for Disease Control and Backention offers very simple and adults.
Here are the BMI percentiles and weight statuses for children ages 2 to 19.
The BMI-for-age percentile shows how a child’s weight compares to that of other children of the same age and sex. For example, a percentile of 45 percent means that the child’s weight is greater than that of 45 percent of other children of the same age and sex.
BMI is considered an inexpensive and easy-to-perform technique to estimate one’s body fat and weight status, but it does have its limits. It can overestimate the amount of body fat in athletes and other people with very muscular bodies. It can also underestimate the amount of body fat in older adults and other people who experience lost muscle mass.
At the same time, there are many myths related to BMI that people believe blindly. These myths are not accurate and are simply some misunderstandings of what a BMI means.
Here are a few BMI myths you need to stop believing.
Myth #1: A low BMI means you are healthy.
Being obese is associated with a higher risk of high blood pressure, high blood sugar and high cholesterol. But having a low BMI does not mean you are protected against these and other health issues.
People with a low BMI are at a higher risk of developing infections than people who have a healthy weight. This happens as being underweight is often associated with a compromised immune system.
A 2006 study published in The New England Journal of Medicine reports that Korean men and women having a lower BMI are at an increased risk of developing respiratory problems, like lung disease. Also, the risk of death from respiratory diseases is higher in those with low BMIs.
Moreover, thin people can carry unhealthy fat internally. In fact, people who have visceral fat are at a higher risk for heart disease, Type 2 diabetes and cancer.
So, do not assume you will always be healthy just because you have a low BMI.
Myth #2: A high BMI increases the risk of a heart attack.
A higher BMI is associated with the risk of a heart attack, but this is not always the case. It is the amount of body fat that is most associated with heart-related problems.
A 2016 study published in JAMA Internal Medicine studied 4,046 genetically identical twin pairs with different amounts of body fat. The study found that twin siblings with a higher BMI did not have an increased risk of heart attack or mortality.
The study also reported that a higher BMI can be associated with an increased risk of Type 2 diabetes.
Earlier, a 2013 study published in the BMJ found that a higher BMI is a weak risk factor for mortality from cardiovascular disease in south Asians.
Furthermore, a 2017 study published in the Annals of Internal Medicine shows that having a normal BMI does not necessarily protect an individual from cardiometabolic risk.
Myth #3: Eating healthy and exercising means you’ll have a low BMI.
A healthy diet and regular exercise are key factors in maintaining a healthy body. But this does not equate to a low BMI. BMI does not make a distinction between lean muscle and body fat.
Also, bear in mind that muscle weighs more than fat, hence someone who adds exercise and healthy eating to their routine life may look thin but have a higher BMI.
Some people who start working out and eating better may gain muscle mass and weigh more. Also, such people may not suffer from any kind of health problems.
You must also not forget that people can be healthy irrespective of their body sizes.
Myth #4: A BMI indicating you have a normal weight status means you’re healthy.
If you’re an adult with a BMI between 18.5 and 24.9, it is a good sign that your weight is within a healthy range. But this does not mean you are healthy.
In fact, thin people may not be any healthier than overweight people. Your health status depends on a lot of factors, including your genes, your gender, your lifestyle, your diet and lots more.
If a person who has a normal BMI is a chain smoker or heavy drinker, then how can you consider him or her healthy? Smokers and drinkers are at an increased risk of suffering from several health issues, including cancer.
So, never take your normal BMI as a sign of overall good health.
Myth #5: BMI is a good measure of one’s health.
Remember that BMI does not work for all, especially tall and athletic people. Hence, you cannot consider it an accurte measure of one’s overall health status.
A 2016 study published in the International Journal of Obesity reports that when using BMI categories as the main indicator of health, an estimated 74.9 million U.S. adults are misclassified as cardiometabolically unhealthy or healthy.
Also, doctors should not only focus on the number on the scale. This can lead one to ignore health issues. So, when you go for a health checkup, ask your doctor for a complete checkup.
Myth #6: BMI can be effectively applied on individuals as well as across populations.
Contrary to the popular conception, BMI is just not suitable to measure the health and obesity status for individuals.
However, it is good for measuring obesity across different populations. In fact, it is a useful tool for population-level measure of overweight and obesity status.
The BMI formula was originally created by a mathematician, not a doctor. It is a simplistic weight-to-height ratio that does not take into account one’s age and body composition and hence cannot be used to predict per person obesity and health status.