Yesterday we talked about childhood obesity and how a high BMI can make children live 2 to 10 years less. When talking about BMI, the reference values of adults are usually offered, however Children's BMI is valued differently. and a BMI of 20, which in an adult is an extraordinary weight, may indicate significant obesity in a young child.
For this reason it is important to know how to calculate the body mass index and, once we obtain the data, know how to interpret it in the tables that WHO offers on its website.
Below we will explain how to do it so you can see on what BMI are your children and assess whether they are in normal weight, overweight, obese or if they are underweight.
How to calculate children's BMI
The BMI of children is calculated in the same way as in adults, applying a simple formula in which the weight of a child in Kg is divided by its height squared, in meters.
For example, if we have a 2-year-old child weighing 14,340 kg and measuring 82 cm, his BMI will be 21. The formula for obtaining it would be as follows: 14,340 kg / (0.82 m x 0.82 m).
A priori, a BMI of 21 sounds like a child with normal weight (at least in adults it is like that), however This two-year-old child has an important obesity and therefore we must know what values are normal for each child.
Assessing our child's BMI in the WHO tables
WHO offers on its website, in addition to the tables with growth patterns, tables with BMI (in English BMI) for children up to 5 years.
Once we have the value (BMI) of our child, we must select the table that corresponds according to sex:
BMI table for children from 0 to 5 years old (click here to enlarge):
BMI table for girls from 0 to 5 years old (click here to enlarge):
Once we have it in front of us, we position our son according to his age and according to his BMI (BMI). The point on the table in which our child appears will be part of one of the percentiles (between 3 and 97) or it will go out above or below.
According to our example, the 2-year-old boy with a BMI gets 21 from the table above (and much), as you will see below:
What percentiles mean when assessing BMI
Once we know what our child's percentile is, we will look at what that percentile means:
- Under 3: boy or girl in a low weight situation.
- Between 3 and 85: boy or girl with normal weight.
- Between 85 and 97: overweight boy or girl.
- Older than 97: boy or girl with obesity.
It follows that everything that is not between the 3rd percentile and the 85th percentile should be assessed by a pediatrician, to act accordingly if necessary, providing dietary guidelines and educational advice to help achieve healthy habits that affect weight (in most people, healthy habits cause a normal weight).
