"It's not about treating obese people badly," he said. "It's about people paying for the costs that they are imposing on the airline or in general."
Singer is a mega-commuter, flying from his home in Melbourne, Australia, to the States. He thinks that on a flight from, say, Melbourne to New York, an obese person should face a roughly $30 surcharge.
"The airline is just one example that I've chosen," Singer said. "Buses and trains may have to provide wider seats. Hospitals have to have stronger beds, even having to have extra-large refrigerators for their morgues. So it's not hostility to obesity. It's just saying, where people are paying, why should other people who are lighter be subsidizing those who are heavier?"
There are plenty of people who are on board with Singer's idea, like MeMe Roth, the founder of National Action against Obesity, who has very strong opinions about the wide-ranging impact of obesity.
"I don't want the person next to me on top of my seat, or coming underneath the armrest because I've paid for my whole seat," she said. "It's nothing personal against them."
And there are plenty of people who sympathize with Kenlie Tiggeman. Brandon Macsata, an advocate for passengers' rights, has become a leader in the "fat acceptance" movement and thinks an obesity surcharge would spark outrage.
"These aren't durable goods being shipped from point A to point B. This isn't cattle being shipped to a livestock farm," he said.
But making overweight people pay more for their flight might ultimately be bad for business. While Roth argued that airlines weigh bags discreetly, Macsata said, "That's a bag. It's not a person."
In fact, Macsata's fat acceptance group has proposed that airlines provide a row of extra wide eats for larger passengers at a higher price, which they can buy voluntarily.
Pressing forward with her lawsuit, Kenlie Tiggeman said she is not an advocate for obesity, but wants to be treated with respect.
"Shaming people isn't the right way to do it, then you'll just have a lot of depressed people," she said. "I don't care if I have to pay more, just tell me what I have to do and I'll do it."