As a person of larger size (i.e. fat), I find most of this thread very offensive, particularly BOFH's post which although at first reading seems tongue in cheek, but using the "n-word" replacement test, it's actually extremely offensive. You can't just make this stuff up for a joke without believing in it as well.
Tips for fat passengers:
a) Check for MD80s, 757's and ancient 737's. They suck and you WILL need a seat belt extender if your BMI > 30. Newer 737's and all Airbus do not need such an item as they have adequate girth.
b) Be wary of going for the extra legroom on over the wing exit rows in old 737's as these have hard fixed sides to the seats and must be incredibly uncomfortable for all concerned except children, jockeys and very small women, all of whom are ineligible for that row.
c) If you are seated next to a steroid abuser, it's never going to work. One of you has to ask for a smaller row mate. My most uncomfortable flight ever was next to a buff gentleman who was easily a metre wide.
d) Newer 737's and Boeings and pretty much all Airbus have curved meal tables. These make it easier to eat the ever diminishing "meals" they serve.
e) I tend to just put up the armrest. One airline I travelled on (a Delta subsidiary?) just made everyone leave them up on the ancient 757 as not only was seat pitch extremely uncomfortable, seat width was a joke. I wish more airlines had this policy, particularly in cattle class.
f) Travel at non-peak times and aim for the aisle near the front, or seat 1A on a low cost carrier. This has the most space, will most likely not have a passenger next to you, allowing you to use the middle table.
I remember not even six years ago being able to use my Dell laptop (larger than my current Mac) on an Ansett 767 in cattle class. Somehow, over the last few years, it's become increasingly difficult to use laptops in planes, even my smallish Mac - except in business class. Seats have been getting smaller. In the same time, I've lost circa six kilograms, so if anything I'm smaller now too, but it's not helping.
For all you folks suggesting that I and the other fat SLF lose some weight, you should try it sometime. It's the hardest thing you'll ever have to do. Unlike alcohol or drugs, you can't stop eating, and for very frequent business travelers like me, I can't easily pick or choose my carrier, when I fly, the class I fly in, or where I can eat once I am at my destination. Eating on the road is one the major reasons I'm the shape I am in.
Saying that, if there's any other SLF wanting to start a weight loss program, me and the wife are losing weight to start a family. You're welcome to join us. We could start a thread, share exercise and food tips. That technique helped two of my friends lose a combined 75 kg.
Andrew