Collage of fruits, vegetables, and whole grainsA group of 10-year-old girl scouts was asked, "What makes up a healthy diet and lifestyle?" Their answer was simple: Eat fruits, vegetables, and whole grains; drink water; don't eat candy; and play.

Marion Nestle, a New York University nutritionist, agrees with the girls. Her recommendations: "Eat less, move more; consume plenty of fruit, vegetables and whole grains; and avoid too much junk food."

In his 2008 book, In Defense of Food, Michael Pollan's recommendation is also simple.

"Eat food. Not too much. Mostly plants."


Why don't we eat a healthy diet?

If eating a healthy diet is as simple as Pollan says, why are there so many people who don't do it? We outline two important factors below.