Lots of factors...Where I now live, the 4 Corners area of the US, "Fitness" runs about 5,371,887th on most people's lists of things to do. There definitely are fitness enthusiasts, as this is a big mountain biking and skiing region.
The locals who can afford the mountain bikes and the $100 a day to go skiing are on the more fit end of the spectrum. However, most of the people who engage in fitness activities around here are not locals but tourists. This area is financially depressed which not only affects one's ability to participate in sports, but also affects food choices. Ever notice it's more expensive to eat healthy than to pile tons of marked-down, low-end beef roasts into your cart? "Buy one get one free" happens a lot in the meat case, but if supermarkets did that with lettuce and vegetables, it might entice a low-income family to eat better.
I've noticed a general "laxness" in parents when it comes to healthy eating habits. My daughter has a friend who spent several nights here during the holidays. Imagine my shock when, at 9:00 p.m. I heard a soda can pop open! The kid decided this was an appropriate time to drink a Coke! I dashed into the kitchen saying, "No, no, no, no, no...Between the caffeine and the sugar, you'll be bouncing off the walls all night." This kid has horrible teeth and has begun packing on pounds, as she's just passed puberty. (Her entire family has terrible teeth and seriously compromised eating habits.)
Even at our least fit, we've tried to serve balanced meals, get some form of exercise into our lives and use common sense about sweets and other junk. Lots of people like a great hamburger topped with a wonderful cheese and properly prepared french fries as a treat. If a parent bases his or her child's diet on this kind of high-fat fast food, their kids are in for an uphill battle, weightwise. If a parent is a lousy eater, they pass this onto their children simply by observation. That's the scary part.
Food is sex for the stomach.