Weight diary and BMI calculation

The calculation of the BMI is a weight evaluation system.

What is BMI?

The calculation of the BMI is a weight assessment system, referred to the risk of disease, proposed for the first time by the Belgian scholar Adolphe Quelet (1796-1874).

Through the solution of a formula that requires two known values, stature and weight, the calculation of the BMI offers a coefficient to be inserted in a special evaluation grid that allows to establish: normal weight, underweight, overweight and obesity (the latter, possibly classified in different severity levels).

What is BMI for?

Since its invention, BMI has progressively become a leading diagnostic tool for assessing a person's weight and position relative to normal or normal weight - statistically associated with the lowest risk of getting metabolic pathologies and not only.

However, due to the lack of precision (it does not take into consideration the size of the skeleton and the musculature) and the application limits it entails (it must not be used for the evaluation of children and elite athletes), today the simple BMI is partially replaced by more accurate and innovative estimation methods, but certainly less practical.

The most indicated BMI values, if referred to the metabolic-health aspect, are around 21-22 (22.5 kg / m2 in men and 21 kg / m2 in women). However, in one study, British men were most attracted to female models with BMI of 20.85; this value, which has no predictive significance on the risk linked to replacement pathologies and various complications, offers instead a snapshot of the average expectations in terms of "ideal weight" - read the articles dedicated to body image and behavioral disorders food (DCA).

The normal range of BMI (18.5-24.9 kg / m2) is wide precisely because of the subjective differences related to the physical structure of the population. As anticipated, the BMI calculation does not take into account muscle mass (greater, for example, in men and young people than women and the elderly), let alone the differences regarding bone mass and the proportion between the length of the limbs and stature.

Man and women

BMI for men and women

Many argue that BMI should take sex into account, meaning that it is different between men and women. In reality it is an inaccuracy, because what makes the difference are characteristics that tend to be linked to it, but not directly and linearly.

BMI does not consider factors such as the size of muscle mass, skeleton and essential fat. It is known that men have on average a higher musculature and bone structure than women, that the elderly are instead weaker than the young, and that women have a greater percentage of essential fat necessary for reproductive function. With regard to bones, it is possible to integrate the calculation of the BMI with integrative equations that allow you to estimate this variable too.

This does not mean that there are women and the elderly with higher muscle volumes and lower fat mass than most men and young people. This is why the BMI assessment should not be used to estimate a person's weight too precisely and accurately, but simply to identify the risk index linked to overweight and underweight.