Thanks to the popularity of things like Facebook, Playstation and TiVo, it's pretty obvious that teenagers today are getting less physical activity than they were a few decades ago. Or is it? Recent findings from Johns Hopkins Bloomberg School of Public Health have found that teenagers today are definitely heavier than they were 20 years ago, but they're still getting about the same amount of physical activity. Which means, then, that a lack of exercise isn't to blame for the staggering levels of obesity in young adults today.

Of course, if obesity isn't caused by a reduction of calories being burned off, the only other logical explanation is that it's caused by an increase in the calories being consumed -- we're getting just as much activity as we did before, but it's simply not enough to make up for all the extra food we're consuming. In fact, other experts argue that the surge in obesity levels in youngsters is caused by food alone -- exercise habits don't even factor into the equation.

Hey, nobody's saying that exercise isn't important -- it's definitely an essential part of a healthy lifestyle. But when it comes to obesity levels in teenagers, it seems the problem starts at the dinner table, not the couch.

Many people are also pointing fingers at school lunches -- students in Chicago can fill up on nachos five days a week.