Why you can't eat just one: what makes Doritos--and other junk food--so irresistible?

• Author: Barth, Amy
• Position: SCIENCE

Picture yourself reaching into a bag of Nacho Cheese Doritos. You feel the powdery cheese touch your fingers. Your mouth starts watering just thinking about how good it's going to taste. Finally, you pop one into your mouth and start savoring the crunch of the bright-orange tortilla chip as it dissolves in your mouth. But there's a problem: They're so addictive you can't have just one. Before you know it, the whole bag is gone. One small, 21-ounce bag of Nacho Cheese Doritos contains about 25 chips and a whopping 17 grams of fat-that's more fat than some 8-ounce steaks have!

Doritos are so irresistible that it's no surprise they're such a popular snack food. Roughly $5 billion of Doritos products are sold worldwide annually.

What makes this and other fatty foods so enticing? Food scientist Steven Witherly took the chips into his lab in Valencia, California, to find out.

"Basically, everything that excites your taste buds, Doritos has [it]," Witherly says. "They've left nothing out."

Take a bite out of what Witherly learned below.

Eye-Popping Color

Research shows that people are drawn to bright colors. Doritos have artificiol yellow and red colors that make them stand out.

Salt

Salt activates the brain's pleasure center. A 2.1-oz bag of Nacho Cheese Doritos contains nearly 20 percent of the maximum daily salt Intake advised for adults.

Meltdown

When fat-filled snacks like chocolate...