Do pilots and stewardesses have weight limits?
Stewardesses, yes, and from what I hear airlines are real hardasses about it.
Pilots? Dunno.
Maybe this used to be so. But from what I’ve seen, and from this sort of thing
http://www.lieffcabraser.com/united_airlines.htm
I definitely think quality control in this and other respects has been slipping on U.S. airlines at least. I suppose they could still fire you for being too obese to get out the emergency exit, but maybe not even then . . . .
Yea, if they get too obese, the plane will be too heavy to take off. * (unless they add extra rocket boosters to the plane for additional lift) * 
There are no specific weight limits for pilots. You just need to have a Class 1 Aviation Medical. There are some pretty obese medical holders unfortunately. Some airlines have their own medical standards which are more strict.
See…told you so. Never doubt me.
-M
Told who what so?
Who?..What?..Where?..When?..How?
It can be pretty hard to hold onto a Class One medical if you’re significantly obese, though - the high blood pressure and/or type II diabetes kicks in and that’s it, you’re grounded until you fix the problem (if you’re even able to)
Yes. Pilots who have a serious weight problem will quite likely find they have a short-lived career. Even people who are on the heavy side of normal need to be careful that they don’t develop some of the problems you’ve mentioned in their middle-age.
Stewardesses used to have weight limits, but airlines no longer utilize stewardesses, therefore the weight question if obsolete. 
Since I would assume the airlines want to ensure stewardesses can easily maneuver through the narrow isle, shouldn’t size (and not weight) be the only thing that’s important?
I had a nice long post ready last night but the hamsters ate it…
US airlines used to have weight standards for flight attendants, but as the flight attendant job morphed into a career those standards were challenged. Companies can still have hiring standards, but these are usually “weight proportional to height”. Once hired, the only limits are performance of duties. If a flight attendant cannot physically perform the duties required in an emergency then they are not allowed to fly. I’ve seen a flight attendant removed from the schedule because she could not fit through an overwing exit. She was put on paid leave and given IIRC three months to be able to comply, after which she would either return to the line or be let go.
As other people have touched on, it IS possible for a pilot to maintain a Class I medical while obese, but he/she will probably be losing that medical soon. Between the EKG, blood pressure, and diabetes tests the obesity will catch up with the pilot quickly.