Oh, I believe it! When we lived in San Francisco, I was at my fittest weight ever (even high school). We walked everywhere, ate better (IMO) and in general were just more aware.
We moved to Morgan Hill and I packed on 40 (yep 4-0) LBS IN 2 YEARS. Everywhere there we needed a car. There really wasn't anywhere decent to eat within walking distance. I went from 5'10 at 135 lbs to a whopping 175lbs.
Now we are in Jersey (Right over the bridge from Philly) and now I have to be uber-aware of food. Yes....they sell philly cheesesteaks EVERYWHERE!
We still need a car to do anything but I lost 10 lbs so far and I'm hoping for the best.
Shanny