Since the first commercial flight took off early in the 20th century, the average size of humans has gotten bigger.
The average size of an airplane seat, however, hasn't. In fact, they've actually gotten smaller.
You can imagine how difficult it might be, then, to be fat while flying.
Stacy Bias, an animator and fat activist in London, created a short, animated video called "Flying While Fat" that features the actual voices of plane passengers explaining how miserable the experience can be for people of larger sizes.
"I wasn't sure if I'd be able to fit into international airplane toilets and I actually just had to risk it the first time," she said.
Bias boarded the plane, "not knowing what I'd do if I couldn't use the toilet on an eight-hour flight!"
"To combat my anxiety," she continued, "I began compiling the details of my flights — what models of plane, the width of seats, if tray tables worked, if I needed a seatbelt extender, if I could use the toilets, etc."
Turned out, Bias wasn't the only one who faced these problems.
Bias and Dr. Bethan Evans of the University of Liverpool surveyed hundreds of people for the film.
"Fat people on planes are talked about a LOT, but rarely are they spoken with, and even more rarely spoken as," she said.
One woman in the short even detailed how a fellow passenger once complained to a flight attendant very loudly, and in front of her, about having to sit next to someone so heavy.