You can say one thing for Professor Mark Haub: He knows how to make a lesson stick.

Haub, who teaches nutrition at Kansas State University, wanted to prove to his students that weight loss is simply about calories. So, for 10 weeks, the professor proceeded to eat an 1,800-calorie diet consisting of a Twinkie every three hours. He also dined on Doritos, Little Debbies, sugary cereal and other junk food.