BMI calculation: woman, man, the formula (age, weight, height)

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BMI calculation woman man the formula age weight height

The body mass index (BMI) is a measure of a person’s build based on their weight in relation to their height. It can indicate overweight or obesity in adults, male or female.

Extra pounds or not? To find out if you need to lose weight, first calculate your body mass index or BMI. BMI helps to know if our weight is suitable for our size. A BMI that is too high can reveal a overweight even a obesity. Too low, it can indicate that a person is too lean. In addition to the BMI, you can also calculate your IMG : fat mass index.

What is BMI?

Invented in the 1840s, body mass index Where BMI lets know if your weight is ideal, in other words, if it is suitable for your size. In English, BMI is the BMI or “Body Mass Index”. This indicator is used by doctors to assess nutritional status. It thus allows to recognize undernutrition, thinness, overweight or a obesity. the BMI calculationvalidated by the WHO, is based on a formula mathematical simple.

To calculate your body mass index:

  • Note the weight in kilograms: for example 65 kilos
  • Multiply the height in meters by the height in meters (to obtain the height squared): for example for a person measuring 1.70m: 1.70*1.70 = 2.89
  • Divide weight by height squared : 65/2.89 = 22.4

The BMI of a person weighing 65 kilos and measuring 1.70 meters is 22.4. His build is considered normal.

What are BMI standards?

  • BMI < 18.5 kg/m²: underweight
  • 18.5 < BMI < 24.9: normal weight
  • 25 < BMI < 29.9: overweight
  • BMI > 30: obesity

For a BMI equal to or greater than 25 kg/m² and less than 35 kg/m², the clinical examination must be completed by measuring the waist circumference.

Normal BMI pattern and variations. © Catherine CLAVERY – stock.adobe.

What is a normal BMI?

One Normal BMI is between 18.5 and 25. Below 18.5, the individual is considered too thin. Above 25 is overweight. From 30, we speak of obesity.

What is the average BMI in France?

According to the 2020 ObÉpi-Roche national epidemiological survey relayed by the League against obesity in 2021:

  • the “average Frenchman” is nearly 1.77 meters tall and weighs more than 81 kg
  • the “average Frenchwoman” is 1.64 meters tall and weighs on average just over 67 kg
  • the average BMI in France has gone from 25.4 in 2012 a 25.5 in 2020.

What BMI when you are obese?

From a medical point of view, obesity is excess body fat with health consequences. Excess weight leads to an increased risk of metabolic diseases (diabetes), heart, respiratory, joint and cancer. If you want to start a diet to lose weight, talk to your doctor first. To note that the severity of obesity depends on body mass index (BMI) :

  • “moderate” obesity for a BMI between 30 and 34.9,
  • “severe” obesity when the BMI is between 35 and 39.9
  • “massive” obesity for a BMI above 40.

What is the difference between female BMI and male BMI?

The BMI calculation does not differ by sex. The formula is the same for women and for men. The result too. A woman’s BMI, like a man’s BMI, should normally be between 18.5 and 24.9.

What is the BMI of a child and an adolescent?

In children, reference should be made to body curves present in health records. the identification of overweight and obesity in children should be based on monitoring BMI. In addition, the height and weight growth of girls and boys differing very early on, we distinguish BMI curves girl and BMI boy, from birth.

What are the limits of the BMI calculation?

Calculating BMI has its limitations:

  • It is not suitable for pregnant women and the elderly.
  • L’Child’s BMI not based on the same method.
  • Dehydration lowers the BMI while edema increases it.
  • L‘BMI does not specify where the fat mass is located, which is harmful to our health. Thus, a very muscular person can display a high BMI, while he does not have excess fat. Many scientists believe that the waist circumference is more relevant and predictive of a health problem because it testifies to excess abdominal fat (around the organs) which disrupts the metabolism. Excess fat mass located around the belly is associated with an increased risk of diabetes and cardiovascular disease, regardless of BMI. The measurement of the waist circumference and the calculation of the BMI would thus be complementary.
  • An “non-standard” BMI is a warning signal prompting a nutritional assessment more detailed.
  • It is essential to take into account changes in BMI over time: a rapid decrease in weight or BMI should lead to an assessment of nutritional status with the attending physician.
  • The calculation of the BMI is only one element of the nutritional evaluation which includes the clinical examination, the state of health and taking into account the context (sport, pregnancy, etc.).

Whether it is a situation of undernutrition or obesity, the problem of weight or nutritional status, and therefore indirectly of food, is linked to a multitude of factors linked to lifestyle and the environment.

Sources:

Constance Cohort

The state of health of the population in France – 2015 Report Department of Research, Studies, Evaluation and Statistics.

Growth curves 2018, Center of Research in Epidemiology and Statistics Sorbonne Paris Cité (CRESS).

Inserm: Obesity dossier

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