WASHINGTON (AP) -- We know obesity is a health crisis, or every new year wouldn't start with resolutions to eat better and get off the couch. But don't try taking away our junk food.Americans blame too much screen time and cheap fast food for fueling the nation's fat epidemic, a poll finds, but they're split on how much the government should do to help.Most draw the line at policies that would try to force healthier eating by limiting food choices, according to the poll by The Associated Press-NORC Center for Public Affairs Research.A third of people say the government should be deeply involved in finding ways to curb obesity, while a similar proportion want it to play little or no role. The rest are somewhere in the middle.Require more physical activity in school, or provide nutritional guidelines to help people make better choices? Sure, 8 in 10 support those steps. Make restaurants post calorie counts on their menus, as the Food and Drug Administration is poised to do? Some 70 percent think it's a good idea.\That's a start