Man pouring milk into cereal [© SuperStock](Man pouring milk into cereal [© SuperStock] )

Why does the concept of weight loss conjure up images of, frankly, unappetizing foods? Why do carrot sticks always spring to mind?

The answer seems to lie in the common delusion that to pare pounds you have to barely eat, and the calories you do eat should be no more than what's required by a mouse. But researchers are repeatedly finding that food quality is more important than quantity when it comes to weight loss. Combined with adequate exercise, your meals can be regular serving sizes. The food just needs to be, well, wholesome.

“We’ve lost sight of that word—diet,” says Kristina Campbell, runner-up in a weight-loss challenge held in Phoenix, Ariz. “Diet used to mean what your food is for the day, not losing weight.”

Below, Kristina and clinical nutritionist and author of Dare to Lose, Shari Lieberman, Ph.D., pinpoint some essential healthy foods for anyone who wants to lose weight and/or maintain good health.

1. Yams and sweet potatoes

These are great diet foods because they’re low on the so-called glycemic index, says Lieberman. The glycemic index measures the values of various foods based on how quickly they break down and are absorbed into the bloodstream. The slower the digestion, the lower the score, the better the food is for regulating blood sugars, insulin, and overall metabolism—all of which affect fat deposition.

2. Oranges, apples and grapefruit

Lieberman recommends these particular fruits because they contain high levels of the soluble fiber pectin. Fiber slows digestion, helps eliminate toxins stored in body fat, and gives you a feeling of fullness.

3. Killer sandwiches

To lose 40 pounds in 21 weeks, Kristina relied on plenty of hearty sandwiches stacked with vegetables, such as tomato, cucumber, sprouts, lettuce and onion, as well as deli meats—but always oven-roasted turkey over anything vacuum-packed. For bread choice, Campbell suggests anything brown with lots of seeds and heavy grains you can actually see, because less-milled ingredients contain much more fiber.

4. Cereal

They can be a little hard to find, but low-sugar cereals packed with protein and fiber are hitting the market. The Kashi brand is one of the best, says Campbell. “I eat my cereal with skim milk and blackberries or raspberries, which contain about 8 grams of fiber per cup. That's like three or four slices of bread!”

5. Salad

"If you eat a salad, make it valuable," suggests Campbell, who's also a former five-star chef from New York City. "Get field or Asian greens and add a yogurt-based dressing. Plus you need a ton of vegetables and some good lean protein, like grilled salmon."