The 'YOU Docs'—Dr. Mehmet Oz and Dr. Michael Roizen—are back with an urgent wake-up call for millions of Americans. "We're the fattest [country] and we have the highest incidence of suffering from obesity," Dr. Oz says.

How did we become so fat? Dr. Oz and Dr. Roizen say the cause of our expanded waistlines is our larger portion sizes. For example, the typical cheeseburger now is four times the size it was in the early 1980s. You can get an order of french fries that is nearly three times as large as an order from 20 years ago. At the movies, you used to get five cups of popcorn. Now you can get a tub that holds a whopping 11 cups.

Even our plates are bigger! The typical plate from the 1970s was nine inches across. Now they're anywhere from 11 to 13 inches across.

Obesity and a sedentary lifestyle are the leading causes of premature aging, but it's not too late to turn your health around. Dr. Oz and Dr. Roizen say you can start to reverse your bad health in just four weeks.