There’s a reason your gut expands while you’re in the air — and no, it’s not because of the sodium in the aeroplane food.
Turns out the increased altitude causes the gas in our intestines to expand by 30 per cent, as Dr. Peter Hackett, director of the Institute for Altitude Medicine, told Conde Nast Traveller:
The ‘cabin altitude’ of most planes is equivalent to about 7000 feet, he says. And as science has it, all gases — including those in your gut — expand as pressure decreases (or as altitude increases), Dr. Hackett explains. “Gas in the intestines will expand about 30 per cent with a cabin altitude of 7000 feet.”
That expanded gas has to go somewhere, which is why you often end up muffin-topping your aeroplane seatbelt or discreetly trying to eke out a fart.
It’s also a good reason to wear loose clothing on a plane, especially if you’re on a long flight — and to stand up, every once in a while, and crop-dust the aisle on your way to the aeroplane lavatory. (Don’t worry, the flight attendants are doing the exact same thing.)