When customers ask for a soft drink with their combo meal, chosen from a red menu board, the clerk reaches into a red cooler and hands them a Coke.

It can be easy to fall into a fast food rut on the road, but while a drive-thru combo meal may satiate your appetite, it won't help your energy level in the long run.

A study in the Journal of Public Policy &Marketing shows that compared to ordering a la carte, you pick up a hundred or more extra calories by opting for the “combo” or “value meal.