Welcome to Walking the Walk, a feature that takes a deeper look at commonly shared diet and fitness advice. Every other week, I'll choose one piece of advice and practice it for seven days. Then I'll report back on what I discovered about making it work in real life and how it affected my own personal fitness -- and how it ultimately can affect your own efforts.

It's weird to think that eating something that your body never actually digests can improve your health, but that's the story of fiber. Fiber is the part of a plant food that can't be absorbed by the body, so it virtually just takes a ride through your intestines.

But just by being there, fiber does your body good. It improves the health of your digestive track by moving things along. Soluble fiber, or fiber that dissolves in water, can absorb sugar before it's digested by the body, which can help prevent and control diabetes. Insoluble fiber prevents constipation and may lower the risk of colon cancer. Fiber can even help lower cholesterol levels.

In addition to all that goodness, fiber-rich foods help you stay full, a definite benefit when you're trying to lose or maintain weight. And since foods that are rich in fiber are also full of antioxidants and other healthy nutrients, you're getting a double whammy of good nutrition.

Most experts recommend that we get 25 to 35 grams of fiber a day. My challenge this week is to do just that.