BMI = weight (kgs)/height˛ (metres˛)
The breakdown of BMI categories is as follows:
<18 Underweight
18 - 25 Acceptable healthy weight
26 - 30 Overweight
31 - 39 Obese
41+ Morbidly obese
For those considered obese or morbidly obese at the time of check in, rather than how many seats they require, an independent medical exam for fitness to travel should be mandatory.