I am not small fry myself at 5'10" 230 lbs, but I had the unfortunate experience of being next to the largest human I have ever seen on an airplane. It was on a CRJ too. 350-400 lbs, 6 foot 7, about as wide, this had to be the starting offensive lineman for some professional team somewhere. Not just fat either, just a HUGE human being.

When he got down into 7C, with me in 7D, my entire body was pressed into the side of the plane, I could barely breathe. This is not an exaggeration, whatever you are imagining, make it 3 times worse. I immediate told the FA I needed to be re seated, honestly I could not understand why UAL did not require this person to buy two seats. I told the guy, "dude, I'm sorry, but I have to move, I cant fly 2 hours like this, you need to consider buying two seats when you fly". Surprisingly he did not kill me, crush me into dust or do much other than grunt. I can imagine he was about as pleased about flying a CRJ as I was to have him as a seat mate.

Most fortunate for me, there was one empty seat on the aircraft, and the 1K sitting in the one next to it looked very annoyed at having me as his guest, to which I replied, "tough #%$ pal, I cannot fly 2 hours to Knoxville squeezed into the wall of the plane".

It's bad enough in a 757, but now that UAL just went CRJ on LAX to PDX I am worried this is going to become increasingly common for me. Ill be forced to upgrade on these dinky 2 hour flights just to have enough space to breathe.