A Larger Variety Of Color Means You Will Eat A Much Larger Portion
Variety, or even simply the illusion of variety, is enough to trick our (way too easily tricked, we're realizing) brains into overeating. The big lump of mush upstairs is still just like a child -- show it too many bright colors and it gets overstimulated, then starts making poor decisions.
The way food is presented is something seemingly small that can have a massive effect on what you end up putting in your mouth. A paper published in the Journal Of Consumer Research looked into how the organization (or lack thereof) of food portions can influence overeating. When adults were offered a bowl of jelly beans totaling six different flavors, they ate freaking 69 percent more than they did when the same six flavors were distributed in different bowls.
Another experiment saw different groups of participants receiving the same amount of M&M's, but in 10 colors versus seven colors. Those participants who had the 10-color batches ended up gobbling more candy orbs.
THE BEEF INDUSTRY: [reads study] By gum, we've cracked it! Rainbow tripe!
The researchers already knew from previous studies/breakups that people eat more when there's more variety, but the significance of the candy experiments is that they confirm you don't actually have to add more flavors to make this happen -- just make it look like you did. In this case, there was no actual disparity in variety, but the illusion of it was still enough to make people go, "Wow, look at all these options! Better keep eating more."
For restaurants, this means they can trick you into eating more just by organizing the food in a certain way. The meat at your local buffet might be in different trays, but they're still all made of horse hooves and pig guts, so don't let them deceive you -- one serving should be enough.