After a long day at work, sometimes sticking to the TV is all you want to do. But while watching a "Seinfeld" rerun for the 100th time might help you de-stress, it might also be causing irreparable damage to your health. Watching TV has been linked to a multitude of health problems and unhealthy lifestyle choices - and experts say the younger you start watching, the worse they become.TV viewing is a major contributor to the obesity epidemic gripping the nation, chiefly because the more time you spend in front of a screen, the less time you spend active, says Carole Lieberman, a Los Angeles-based psychiatrist who specializes in the psychological and physical impact of TV, movies and other media. "There's a reason why people who sit and watch hours upon hours of TV are called couch potatoes," she says.

"The more they sit and watch, the more they grow into heavy potato-like blobs."A 2003 study in the Journal of the American Medical Association found that over six years, for every two hours a day women spent watching TV, their risk for obesity increased by 23 percent - and the effect is even larger in children. Kids today spend an average of seven-and-a-half hours per day looking at a screen, and according to a 2011 study in the journal Elsevier, those who watch more than five hours per day are more than twice as likely to be obese as those who watch two hours or fewer. The lack of activity also ups your risk for diabetes and cardiovascular disease, according to a 2011 JAMA study, which found that for every two hours of TV you watch, your risk of diabetes increases by 20 percent, and your risk of cardiovascular disease increases by 15 percent. Many people don't realize that the hours you spend inactive really add up, Lieberman says.

"It's bad enough that many of us spend our workdays sitting in front of a computer, but compounding it by sitting in front of TV or in movie theaters just adds insult to injury."Five hours of watching TV appears to be the break point, especially when it comes to teen smoking. A 2002 study published in the journal Pediatrics found that 10- to 15-year olds who watch five hours or more of TV per day are at a nearly six times higher risk of smoking when compared to those who watch less than two hours. "Teens are particularly susceptible to becoming first-time smokers if they see 'cool' characters puffing on cigarettes," Lieberman says. Excess TV viewing is also linked to emotional problems that can exacerbate all these problems, says Simon Rego, director of psychology training at Montefiore Medical Center and Albert Einstein College of Medicine in New York. "It's linked to lower self-esteem and a feeling of sadness," he says. "This makes us more prone to drink, smoke and live an unhealthy life."So what is it about TV that's causing this effect? A lot of it has to do with advertising, Lieberman says. "TV commercials, filled with mouthwatering shots of high-calorie foods, just beg you to get up and go to the kitchen to get something to eat," she says. "And movies have become synonymous with popcorn; such that you are drawn in a hypnotic trance to the lobby counter where you fill up on popcorn, candy bars and other sweets."That trance is a form of conditioning, Rego says. "People get zoned out while they watch," he says. "They become so engaged during the program that they don't realize that they ate an entire bag of chips, drank an entire 2-liter bottle of soda or smoked a pack of cigarettes."Eventually, these actions become so intertwined with the act of watching TV that doing one without the other seems incomplete, Rego says. "Before you know it, you get cravings based on what you're watching," he says. "It's like how beer, sports and wings just seem to go together with a football game."