# BMI limits in interpretation in people with high/low heights

In a study, I measure BMI of a large sample of adult people.

Among them, there is some who have very low and very high height.

As I can read on the internet (like here or even in the wiki, for instance), BMI is not relevant for very short or very tall people.

Some math professor even wrote an article with a "better" calculation of BMI, but with a very low impact in science world (didn't find it on pubmed) so it's not really peer-reviewed.

Let's take some examples, assuming "normal BMI" is 21:

• for a 110cm tall adult, ideal weight is 25kg
• for a 130cm tall adult, ideal weight is 36kg

These weights appear really low to me. Note that dwarfism cutoff is 145cm in France.

My question is then the following: How could I choose a cutoff on height to exclude BMI values ?

NB: I didn't find anything on pubmed nor on google scholar, but maybe I missed an important article

• I don't really know much about this subject, but I doubt there is a precise cutoff. Isn't it simply a continuous thing? Gradually, the more you move away from mean height (in either direction), the less value the BMI measurement has. One thing you could do is a weighted analysis, with more average height people having heigher weight. – Eff Jun 29 '18 at 8:07
• I don't think this has been studied this precisely but I agree, it should be continuous. Still, I guess it is not linear (x3 maybe?), so there should be a value or a range of value where it become reasonable to think BMI is not relevant anymore. – Dan Chaltiel Jul 3 '18 at 9:53