Re: Amadeus
That would make sense. A BMI of 21 could be the baseline and every point above or below could translate to a, say, 5% surcharge or discount, respectively.
It may even have a positive effect on the global obesity crisis.
Granted, I may be a wee bit biased in favor of such a formula as many passengers weigh more than my luggage and I weigh combined...
Interesting related detail: the load limit of passenger vehicles is calculated as "number of seats multiplied by 175 lbs (80 kg)".