Researchers led by Jason Block of Harvard Medical School surveyed over 3,400 children, teens and adults in 2010 and 2011 who regularly ate at popular fast food restaurants such as McDonald's, Burger King, KFC, Subway, Dunkin' Donuts and Wendy's. They were asked to estimate how many calories they had consumed in their meals and were later shown their receipts and calculated how many calories their meals actually contained.
The researchers found that teens underestimated the amount of calories consumed by 34 percent, adults underestimated by 20 percent while parents of school going children underestimated the calorie intake by 23 percent.
"These large underestimations show that diners don't really know what they are eating in terms of calorie content, and they need this information to help guide their choices. hey could get it from the company websites or in some other form in the restaurants, such as wall posters, napkins or cups, but soon they'll be directly faced with it when they see it on the restaurant menu boards before they order their meal. Customers can already do this at McDonald's -- and in some cities", Block said.