Samoa Air, the first airline to charge passengers according to their weight, is now introducing an "XL class" to cater for larger customers.
The Pacific national airline is creating a wider row for passengers who weigh more than 286lb. Samoa has one of the world's highest obesity rates.
The airline's head, Chris Langton, said the XL row would be extended by 12 to 14in and the changes would be introduced by the end of the week.
"Once you're up around that sort of [weight]?...?a traditional seat on any airline is going to be uncomfortable," he told ABC News.
"Quite often the access is difficult, and even the space between the seats is enough that even when you have squeezed into the seats there's no room for your legs. That's where the XL has come in - we do it with shirts and clothing and other things where we have different standard sizes."
Passengers on Samoa Air do not pay for a seat, but a fixed price per kilogram, which varies according to the length of the route.
The passengers nominate their weight and are then weighed, along with their baggage, on scales at the airport. The rates range from about $1 a kilogram on the airline's shortest domestic route to about $4.16 per kilogram for travel from Samoa to the neighbouring nation of American Samoa.
Mr Langton said he believed other international airlines would eventually start charging by weight and modifying their aircraft to accommodate the changing shapes of their passengers.
"The airline industry is going to have to do that - we're going to have to provide a range of seats categorised in terms of weight and maybe some other indexes like height," he said.
Airlines in Australia this week ruled out imposing a "size surcharge" on obese passengers despite acknowledging the extra fuel costs.
Virgin Australia said obesity was a "big issue" and it sometimes weighed individual passengers to assess the weight of the aircraft. "It's something you've got to start to watch very carefully but the last thing we want to do is make customers uncomfortable," said the airline's boss, John Borghetti.
The Telegraph, London