Obviously not in this case (400 lbs) but someone mentioned earlier that 'anyone that needs a seat belt extender is too fat for one seat.' Not true! What about pregnant women??? Many are very large in the abdominal area, and thus need an extender, but not in the hips/shoulders.

My husband and I are COS (he's 350 and 6'4", I'm 250 and 5'9"). We try to travel together, on a 3 seat bank, with an empty between us. Failing that, we get 2 seat banks, and squeeze against eachother. No one else needs deal with us. If that fails, we'll purchase a third seat between. We tried that once and the flight was full - they tried to seat someone there. Embarrassing all around!

If my husband was in the shape he was in high school, he would be 275 and 8% body fat (he was football/weight training), and STILL wouldn't fit in those bloody coach seats. Not everyone that doesn't fit can help it. (I can, though -- I'm just plain overweight, no thyroid problems. Then again, I've lost 70 pounds so far, so I'm working on it!