Want to eat more and weigh less? Think "density" when you're choosing foods.

In nutrition lingo, foods that are low in "energy density" have lots of water and fiber, but little fat and fewer calories. How do they stack up nutritionally? Just fine, according to a new study. For example, a piece of apple pie has about 400 calories; for the same calories, you can crunch on five healthful apples -- and since one or two will fill you up, you'll skinny down. Search for lists of low energy-density foods.

When you eat more foods that are dense in everything but fat and calories -- think juicy melons, pears, cucumbers, broccoli, and berries -- it not only helps keep you slim but also revs up the nutritional quality of your diet.

When researchers compared people on low, medium, and high energy-density diets, they discovered that women who favored foods low in energy density averaged 250 fewer calories a day compared to those in the other groups; men averaged 425 fewer calories. Yet the nutritional quality of their meals didn't suffer. In fact, they had higher intakes of vitamins A, C, and B6; folate; iron; calcium; and potassium.

In other words, eating low on the density scale isn't just good for your waist, it's good for your health; the extra fiber and nutrients fight disease as well as pounds.

Which foods are naturally dense? The stars are fruits and veggies. So although your daily intake should include plenty of whole grains -- and some healthy fats and low-fat protein (beans, fish, lean poultry) -- replace some of these with extra veggies. Later, grab an orange or banana for a snack. Then, watch your waist whittle down.

Need a low energy-density recipe? Try this delicious Broccoli with Black Bean-Garlic Sauce from EatingWell.com.

Low-energy-density diets are associated with high diet quality in adults in the United States. Ledikwe, J. H., Blanck, H. M., Khan, L. K., Serdula, M. K., Seymour, J. D., Tohill, B. C., Rolls, B. J., Journal of the American Dietetic Association 2006 Aug;106(8):1172-1180.