I ask this question in all seriousness.  I am moderately overweight
myself (maybe 15-20 lbs).  But in Eugene Oregon, I see more heavy
people than I see in other places.  And by heavy, I mean 75-300 lbs
overweight.  It seems to be very acceptable, because I frequently see
very heavy families.  I am wondering if anyone has ever conducted a
survey on incidence of obesity, correlating it to weather, education,
income etc.  If so, I would appreciate some insights.

There's nothing better to do in Eugene Oregon, it's got to be the most
boring place on Earth.

Not exactly referring to your question but in the news today:

Overweight 'top world's hungry'
There are now more overweight people across the world than hungry
ones, according to experts.
http://news.bbc.co.uk/1/hi/health/4793455.stm

Barry Popkin
University of North Carolina
Is Obesity a Result of Faulty Economics Policies? The Case of the
United States and Japan
http://www.iaae-agecon.org/AusConf/confprog.html

Ever been to Wisconsin?  People there balloon when they hit 22 or so. 
(Some of the young'uns are not so thin either.)

West Virginia is the most obese state in the United States. This is
going to contradict with my unsubstentiated assumptions, which are:
- Culture: pacific islanders are the most obese ethnic group in the
United States (a fact, not a speculation), and Americans in general
are much more obese than any other nation on earth.
- Weather: If it's cold, people with less means/education exercise less

I'm not so sure it is unique to Eugene, OR.  I was visiting Nashua, NH
a few weeks ago and noticed the same thing. I've never seen so many
morbidly obese people in one town.  I think it's just a function of
being in a small-ish town and not having a lot to do.

Lumberjack ancestor's with no exercise?