How to calculate BMI – step-by-step guide, indicators, normal value, health implications of the result, 15 best online BMI calculators that work effectively.
What is BMI?
BMI, or Body Mass Index, is a measure used to estimate a person’s build. Designed by scientist Quetelet at the turn of the century, this index is a widely used method to assess an individual’s body mass and healthy weight
Why calculate your BMI?
BMI is used to assess a person’s build according to their height. The chances of having high cholesterol in overweight people are greater, so monitoring your BMI is necessary to maintain a healthy heart. With a simple formula, BMI can be calculated regularly at home to monitor your healthy weight.
However, it is essential to note that BMI is not a perfect indicator. This is because it does not differentiate fat mass from muscle mass: you can have a high BMI without necessarily being overweight. Other factors can also affect your weight, such as age or illnesses such as hyperthyroidism. Additionally, BMI rarely has a low weight range, which could lead older people and those who are underweight to believe they are at a healthy weight. To get a better idea of your situation, your doctor can also measure your waist size, just above the pelvis, or ask you questions about your general diet and your lifestyle.
How to calculating your BMI – Step by step guide
Two measurements must be taken into account to calculate his BMI: height and weight. Using the BMI formula shown below, you can calculate yours just to identify your healthy weight. However, always ask your doctor for advice before making any decisions about your weight.
The Body Mass Index (BMI) is a measure based on two variations: height and body weight. The standard formula applies to adult men and women. The formula is simple: BMI = weight (kg) / height (m 2 ).
BMI formula
So how do you calculate BMI simply? The BMI formula is simple: just divide your weight in kilograms by your height in meters times itself. So, you will just have to follow these 2 steps using your calculator:
Height in meter x height in meter = size squared
Weight in kilograms ÷ height squared = BMI
For example, if you are 1.70m tall and weigh 65kg, your BMI will be: 65 ÷ (1.70 x 1.70) = 65 ÷ 2.89 = 22.49.
In 1997, the World Health Organization (WHO) defined the BMI to assess the possible health risks of overweight in adults, men and women, between 18 and 65 years of age, based on body size.
This index highlights the increase in risk factors . It does not indicate the distribution of fat mass, neither muscle nor bone.
Here are the different categories of BMI endorsed by official health organizations:
> Insufficient weight = <18.5
> Normal weight = 18.5-24.9
> Overweight = 25-29.9
> Obesity = 30 or more
Implications of BMI on health status
If your BMI is below 18.5 , you are considered underweight. The health risks of being underweight include osteoporosis, infertility, and weak immune system. Being underweight can also indicate an eating disorder or other underlying illness.
If your BMI is between 18.5 and 24.9 , this is the weight range considered to be “healthy”. This can lower your risk of developing weight-related health problems.
On the other hand, if your BMI is 25 or more , you are more at risk of developing diabetes, cardiovascular disease, and certain types of cancer..
The higher your BMI, the greater the risk of these chronic diseases.
What are the consequences of overweight and obesity?
Now, it has been proven that overweight and obesity represent risk factors that worsen or promote:
-diabetes
-cardiovascular illnesses
-musculoskeletal disorders
-some cancers
Because reducing your overweight is therefore a sure and quick way to improve your quality of life. Indeed, the clinical studies carried out show that after weight loss, patients have :
-less muscle pain
-no more breath
-better sleep
-fewer chronic or inflammatory diseases
The World Health Organization reports that a high BMI is associated with 21% of cases of ischemic heart disease, 23% of strokes, 58% of type 2 diabetes and 39% of hypertension. A BMI over 30 is also linked to an increased risk of cancer, joint problems, infertility, and mortality.
In a study from King’s College, London, individuals with higher BMIs were at greater risk for several chronic diseases. In addition, obese young people had profiles similar to non-obese elderly people. The “Prospective Studies Collaboration” has shown that the death rate was lowest when the BMI was between 22.5 and 25. At a BMI of 30 to 35, life expectancy was reduced by two to four. years and 40 to 45 BMI, it was reduced from eight to ten years, which is comparable to the effects of smoking.
On the other hand, in a systematic review of cohort studies, people with a low BMI had an increased risk of total mortality and cardiovascular mortality. Overweight individuals had the lowest risk of total mortality and cardiovascular mortality. Obese individuals had no higher risk of total mortality or cardiovascular mortality compared to people with normal BMI. Finally, those with a BMI of 35 or greater did not have a higher risk of total mortality, although they had the highest risk of cardiovascular mortality. The researchers therefore concluded that these contradictory results could be explained by the lack of discriminatory power of BMI to differentiate between body fat and lean mass.
Studies are therefore contradictory as to whether BMI is a sufficiently sensitive tool to really detect excess body fat but also to predict the risk of health problems .
9 Best BMI calculators
1. The Calculator site
https://www.thecalculatorsite.com/health/bmicalculator.php
2) Bluetree health calculator
3) Weight watchers calculator
https://www.weightwatchers.com/uk/bmi-calculator
4) Bupa calculator
https://www.bupa.com.au/healthlink/health-tools/bmi-calculator
5) Mayo Clinic calculator
https://www.mayoclinic.org/diseases-conditions/obesity/in-depth/bmi-calculator/itt-20084938
6) NIH calculator
https://www.nhlbi.nih.gov/health/educational/lose_wt/BMI/bmi-m.htm
7). Healthyweight calculator
https://www.healthyweightforum.org/eng/calculators/bmi/
8). The Calculator soup
https://www.calculatorsoup.com/calculators/health/bmi-calculator.php
9). Atulpeters Calculator
https://www.atulpeters.ng/bmi-calculator.
Limits to BMI
Many people claim that BMI is only a ratio of body weight to height and is not a good indicator of body fat at all. BMI does not differentiate between fat, muscle or bone mass. It also does not provide an indication of the distribution of body fat.
Still, it’s important to mention that obesity basically boils down to excessive levels of body fat, not body weight. The World Health Organization defines obesity as a significant excess of body fat which leads to health risks.
For the same BMI, the degree of body fat can vary. At the same BMI, women tend to have more body fat than men. This tool therefore does not distinguish between the two sexes.
Also, it can lead to a feeling of false security. Indeed, people with a normal BMI may still be at risk of developing diabetes or cardiovascular disease depending on the distribution of body fat (abdominal or not). Also, individuals with a normal BMI but who are smokers, sedentary and / or with very poor eating habits may be at as much risk of health problems if not more than another individual with a higher BMI but who has healthy ones. life habits. In short, by using only the BMI, we cannot identify all the people at risk.
Finally, in people in the process of changes in lifestyle, with modification of the diet and muscular exercises, it is not rare that the weight moves little on the scale and therefore that the BMI does not change. more. On the other hand, many changes may have occurred: increase in muscle mass, decrease in body fat, better distribution of body fat, for example. BMI therefore cannot reflect all of these healthy bodily changes.