Even the most un-choosy eater cares at least somewhat about the visual appearance of food. A food item that looks “off” somehow will trigger a natural aversion to spoiled food.
This aversion to bizarre looking food can be used to help people maintain a healthy diet!
The process is as follows: certain foods that are especially high in calories can be modified with food coloring to look completely disgusting.
So for example, we could have french fries that are dyed a dark purple, or a piece of white bread that has been dyed gray.
Fig. 1: Food that looks “off” (maybe it’s the wrong color, or has a disgusting oily sheen to it) will be less likely to be immediately devoured without a thought.
Fig. 2: Restaurants can also help out by modifying their food. Instead of a normal delicious-looking hamburger and fries, here we have a strange dyed monstrosity. Maybe more people will order a salad now. (In order to prevent the salad from being equally caloric, the dressing would have to be dyed as well.)
This is the ultimate culinary tip for the discerning gourmet.
PROS: Extremely low-cost, helps deter over-eating.
CONS: Does not work in low-light conditions (for example, when ordering food at a movie theater).