First it was bran and fiber, then vegetarian pasta fests, then low-fat everything. Now, the popularity of low-carbohydrate, protein-rich diets is sweeping the country. But is there one weight loss diet out there that's better than others?

The truth is, there is no fad diet with all the answers. If there were, we wouldn't be a nation where two-thirds of Americans are overweight or obese. The chronic diseases associated with this obesity epidemic, including heart disease, cancer, diabetes, and high blood pressure, cost the country $117 billion in 2000 alone.

So what constitutes a healthy weight loss diet?

A diet built from whole foods -- fruits, vegetables, whole grain products, and lean proteins -- that is rich in fiber, vitamins, and minerals and low in saturated fats and sweets is what we should strive for, says Amy Joy Lanou, PhD, nutritional director for the Physicians Committee for Responsible Medicine in Washington, D.C.

What Color Is Your Diet?

It may sound overwhelming, but experts say it's simple.

Start with color. The more color you have in your diet, the better.

Consume colored vegetables with reckless abandon, says fitness and nutrition expert Mark Sisson. To the extent that you can make multicolored vegetables dominate your diet, you're going to be the healthiest you can be.

Vegetables are the best carbohydrates you can eat. They're high in fiber and full of vitamins and minerals. Choose veggies over carbohydrates like pasta, rice, or bread, which have a high glycemic index. These carbs create a spike in blood sugar, causing you to be hungry again sooner and eat more. With all that easily accessible sugar in the bloodstream, the body burns it and stores fat.

In addition to vegetables, many fruits, including apples, oranges, pears, grapefruits, and berries are good, low-glycemic-index choices, says Shari Lieberman, PhD, clinical nutritionist, exercise physiologist, best-selling author, and nutrition counselor.

And avoid processed foods as much as possible, says Lanou.

We rely too much on highly processed foods, she says, from crackers and frozen low-fat dinners at the grocery store to fast food on the road.

Bad Choices, Good Choices

The fewer ingredients an item has, the better, says Lanou. An apple has not become something else. Even as applesauce, the ingredients are apples and water (if you get the unsweetened kind). But when you look at the label on a box of crackers or a frozen dinner or even a can of soup, that list can get long and include many chemicals and preservatives.

Lanou and Sisson recommend staying away from animal-based saturated fats, like butter and cheese, and trans fats found in processed foods, such as some margarines and doughnuts. Use plant-based fats like olive or canola oil instead.

Choose lean proteins like beans, lentils, soy, certain fish, chicken, and vegetables like broccoli or cabbage-based vegetables. That's right -- 39% of the calories in broccoli come from protein.

Eating smaller portions is a great way to cut calories. Especially at restaurants, portion sizes are completely distorted, says Lanou.

A serving size is 10 French fries, she says, yet about 50 come in an order.

Try to relearn what it means to feel full, she says. Full is not in pain, full is no longer hungry.