Eat more food, feel full all day long, and lose weight. It sounds too good to be true, like one of those fad diets that promises to help you shed 10 pounds while you watch TV. But this one is real. It's not that you can eat more Snickers, more pizza, or more sour-cream-and-onion potato chips. However, if you eat more foods that are considered low-density, such as fruits, vegetables, and soups, you can lose weight.

In fact, one study by Penn State University researchers found that obese women were able to lose more weight by eating 25 percent more food on a low-fat, low-density diet than fellow dieters who ate less on a low-fat diet only. Over a year, the women on the low-density plan were able to lose an average of nearly 18 pounds, compared with those on the low-fat plan who lost 14 pounds on average. The plan worked so well because participants felt full but reduced their caloric intake.

Ready to try it? Here are six suggestions on how to eat more and weigh less.

1. Eat more ... colorful foods. Make a bright, bold statement by eating vibrant fruits and vegetables. They should make up about half of your meal, according to the American Dietetic Association (ADA). Remember veggies aren't just boring greens: Add some juicy red tomatoes, bright purple eggplant, or orange sweet potatoes to your dinner plate. For breakfast and lunch, try to incorporate a banana, a handful of berries, or a slice of melon. Such a colorful palette of foods will not only allow you to eat larger portions and fill up on fewer calories; it's also a great way to get important vitamins and minerals, reports the ADA.

2. Eat more ... fiber. Fiber is the perfect diet food because it allows you to feel full for a long time and takes a while to digest, but doesn't contain a lot of calories or fat. Vegetables like peas, green beans, broccoli, and spinach are excellent sources of fiber. You can also get fiber from eating lentils, beans, and whole grains. It's easy to add more to your diet by mixing black beans into your favorite casserole, putting spinach and chick peas in your salads, or serving pasta tossed with lots of broccoli, zucchini, yellow squash, and other vegetables.

3. Eat more ... lean protein. Eating more low-density foods doesn't mean you should cut out sources of protein from your diet. You can still enjoy lower-fat meats like pork and beef tenderloin, sirloin tip, and flank steak. Be careful to trim visible fat and to eat only one portion, which is about the size of a deck of cards, according to the National Institutes of Health. Other sources of healthy protein include nuts, fish, avocados, and beans.  

4. Eat more ... soup. In addition to being a tasty low-density food, soup can also help you reduce the amount of food you eat during meals. A study by University of Texas Medical Branch in Galveston, Texas, found that people ate 20 percent less during their meal when they ordered soup as an appetizer. The researchers speculated that the soup made the people studied feel fuller and slowed down gastric emptying.

5. Eat more ... for breakfast. Research consistently shows that skipping breakfast will make you hungrier and more likely to overeat later in the day. Surprising, it's not just that people who eat breakfast are less hungry at lunchtime; they're also less likely to eat late at night, according to the ADA. The best breakfast foods to eat are oatmeal, fruits, whole-wheat toast, whole-grain cereals, and yogurt. You're better off staying away from doughnuts, bacon, and Danishes whenever possible.

6. Eat more ... often. Rather than eating a few large meals, try to eat smaller meals and snacks throughout the day. Nibbling or grazing helps to jump-start your metabolism, allowing your body to process the calories more efficiently, according to a study published in the British Medical Journal. The best thing about this plan is that eating so often means you never feel hungry.