As studies have indicated, the type of neighborhood a kid is raised in (Int J Obes Relat Metab Disord. 1992 Mar;16(3):169-75), socioeconomic status (SES), and if two parents have jobs can influence whether or not a child is overweight (Prev Med. 1999 Mar;28(3):293-6). I did not fully review the articles above, but did read the abstracts, so take them with a grain of salt. But all three items above tend to be correlated, meaning, those who have lower SES tend to live in rougher neighborhoods and both parents have to work to pay the bills. It makes sense that there is a higher prevalence of overweight kids in these communities because parents don't have as much control over what their kids eat (lack of supervision) and kids cannot really exercise in unsafe neighborhoods. While this explains the epidemic in urban kids, it doesn't get at the heart of suburban/rural kids.
Today I was at the gym and saw a parent working out their overweight child, a child that looked to be eight years old or younger. A policy at the gym requires only 12+ year olds the ability to work out with parents, so I brought this to the manager's attention (since I've gotten to know him a little bit) because I was concerned for the child's safety (equipment being too big to work the correct muscles). But this got me thinking... Children should be exercising by being involved in a sport that they are interested in. If parents have enough cash to belong to a gym, I'm pretty certain they have enough to enroll their kids into a recreational sport. Basketball is relatively cheap in comparison to other sports. OR better yet, go outside and play catch with them, both would then get exercise.
I have always been taught that being a parent means sacrifice. It just seems to me that some parents are stingy putting themselves and their needs before their kids even when they don't financially have to.