Brian Wansink, author of the book "Mindless Eating," co-authored a study of what customers choose at some popular fast food places. He spoke about it on The Early Show Tuesday.
The study, in the Journal of Consumer Research, finds people eating at outlets of the Subway chain are more likely to order higher calorie drinks and/or desserts and other items to go with their meals than people eating at McDonald's, even when the meals themselves have identical calorie content.
Subway advertises the health benefits of many of its menu items, while McDonald's doesn't promote most of its choices that way. And that seems to lead people to assume Subway's menu is healthier across the board, even though only certain offerings are.
The study shows a so-called "halo effect" -- essentially, that Subway's supposed health factor puts a "halo" over unhealthy sandwiches, drinks, desserts and side dishes that customers also order.
In the end, the study concludes, people eating Subway's highest-calorie items tended to take in more calories than people ordering Big Macs, because their underestimate of the calories in the Subway items left them with the mistaken impression they had room for more.
To watch the segment,
To read an excerpt of "Mindless Eating," click here.