I got my hands on the height, weight, position and playing years for all the NBA players since the beginning of the league (data from www.basketball-reference.com). What can we learn from it?
First, let's plot all of the NBA players on a weight vs. height figure:
I marked the body mass index (BMI) categories in the background. About half the NBA players would be considered overweight and a bunch even obese according to BMI. There are 13 players in NBA history with BMI over 30 about 4 are active through 2015 (Jared Sullinger, Sim Bhullar, Elton Brand and Glen Davis).
I also added myself as a black dot on the figure. I would say I'm not a total outlier. The player with the most similar weight and height to mine is Nate Robinson. I would say we have about the same body type. Seriously!
Here is how the weight and height changed over the years:
We see a little dip in the weight during the late 70's to early 80's. If we plot the BMI over the years that dip is even more pronounced since the average height kept growing during this span:
I showed this figure to a few doctors and their immediate reaction was cocaine. I remember reading about the NBA cocaine era (mid 70s to mid 80s) so this explanation makes sense to me. Does the data show the accurate years of the NBA cocaine era? Did the cocaine problem start in the late 60s?
It is also apparent that the BMI keeps getting larger from the mid 80s until early 2000s. One reason is probably cocaine (or lack off) the other reasons can be attributed to better training and nutrition and a skeptical person might even suggest steroids (but I'm not skeptical).
Here is a plot of the BMI as a function of position:
The BMI increases with "larger" positions.
I tried to see if there is any correlation of BMI and player's ability. There was no correlation found. The only parameter that had any correlation (although very weak) was rebounding %.
Conclusions:
BMI is not a relevant matrix for athletes.
I have the same body type as Nate Robinson.
The NBA cocaine era can be seen in the BMI plot.