An operator that I know charges $2.50 per kg for their freight run over a fixed distance.
90-60=30*2.50*150 + return trips a year = $22,500 in lost revenue for a fat pilot
There are suggestions that 1kg a year on an airliner can cost in the 10's of thousands hence why flight crew are expected to be within a certain weight. That and the fact that if you're a fattie you'll struggle to fit down the aisle. Like it or not, thinner people may have more success in renewing their medicals too particularly if your DAME is a BMI Nazi.