Obesity is certainly a health risk and something that needs to be addressed. However, I think we need a better system than a BMI calculator with more factors than general height and weight. I’m short so for my size losing or gaining 5 pounds can make a difference in how I look but may not make any difference to BMI.There are lots of reasons people can't lose weight. You have no idea about this persons life.
I think there is a full body scan that can be done to show percentage of fat and where it’s located versus muscle. A traditional BMI calculator does not factor in something like muscle mass. I bet a lot of the fit rugby players are classed as obese or at least are in the overweight category