Body Mass Index (BMI)
The Body Mass Index is a method used to assess to what extent a person is in an optimal weight range.
While it is not a completely accurate indicator, since it does not take into account the level of muscle mass, it is quite revealing in terms of indicating whether someone is overweight/obese or too thin.
The calculation of this index is carried out by means of a simple formula, which is Kg/M2, or equivalently, mass (in Kg) divided by height squared.
The result of this calculation is an index, which is generally between 16 and 30, with any value outside this range being considered worrying and likely to cause health problems.
The range considered healthy is between 18.5 and 25.
Factors to consider when calculating the BMI (Body Mass Index)
The Body Mass Index is a measure suitable for adults, meaning people over 18 years of age. Children and adolescents should not be assessed with it, since there are other indices more suitable to evaluate the same objective.
It is not a measurement that can be considered definitive, but its results are sufficiently indicative to consider the need for other tests. In fact, although the BMI is not considered an accurate measure, in 90% of cases its results are usually in line with reality.
In order to know whether or not it is necessary to perform other types of actions, we must bear in mind that body types are very different, and that bone mass or the amount of muscle mass are variables that are not taken into consideration when calculating this index. However, values at the extremes of the range should be considered in particular detail, as they may indicate the existence of health problems.
The different results provided by the BMI are categorized as follows:
- Severe thinness < 16
- Moderate thinness 16 - 17
- Slightly thinness 17 - 18.5
- Normal 18.5 - 25
- Overweight 25 - 30
- Obesity Class I 30 - 35
- Obesity Class II 35 - 40
- Obesity Class III > 40
However, weight is not always directly linked to body fat levels, so there is a possibility that someone whose BMI is between 25 and 30, considered overweight, may simply have a considerable amount of muscle for their height, without having any excess fat to merit such consideration. Also, the differences in body composition between men and women and according to the stage of life in which the person is, may cause this value to yield results that do not correspond to reality.
Therefore, this index should be taken as a valid reference only in some cases, but never as a totally reliable indicator that determines the need to make changes in the diet.