The potato is moving from side dish status to the center of the plate as more Americans realize that the old staple is a nutritious and versatile alternative to high-fat, high-calorie meals.

Rich in vitamins and fiber and low in sodium and fat, the potato is considered a perfect diet food. One medium baked potato with the skin has 220 calories, four grams of fiber, trace amounts of fat and no cholesterol, according to the U.S. Department of Agriculture.

"People have this idea that potatoes are fattening, but that is simply not true," said Marilyn Guthrie, a registered dietitian in Seattle. "Adults could derive almost all of their needed nutrients from a diet of potatoes."

Take the same medium-sized potato and deep fry it to prepare french fries, process it into potato chips or slather it with sour cream and the nutritional profile changes dramatically. One half-pound of french fries has 620 calories. The same amount of potato chips -- which are mostly fat -- has 1,200 calories, said Guthrie. Add a dollop of sour cream -- about one tablespoon -- and the fat increases by 3 grams and the cholesterol by 5 milligrams.

For sour cream aficionados, Guthrie suggests a mock version -- combine cottage cheese or yogurt, skim milk, lemon juice and pepper and blend until creamy.

Americans consume about 125 pounds of potatoes per person each year, both fresh and processed, according to the Potato Association of America, a research organization in Hancock, Wis. About 70 percent is consumed in processed forms -- dehydrated "instant" products, potato chips or frozen varieties like french fries.

As potatoes gain favor, more chefs are experimenting with ways to prepare them. At Twenty One Federal, a restaurant in the District's downtown business section, potato-crusted salmon is a signature dish. The chef shreds potatoes and celery root, tosses them in lemon and pepper and spreads the mixture onto a salmon filet.

The restaurant also offers a light-fare menu that features boiled potatoes served with a vegetable relish. "The key is to come up with new and different ways of presenting the potato," said Charles Schermer, Twenty One Federal's sous chef.

Discerning chefs and potato lovers can comb farmers' markets and specialty food stores for different varieties. Exotic potatoes like the Peruvian blue, a thin-skinned, thumb-shaped blue potato; the Yukon gold, a round potato with yellow flesh, or the Caribe, an oval potato with purple-blue skin, can make meals more flavorful and entertaining.

Old favorites like the Russet Burbank -- known as the Idaho potato -- and the Red Bliss remain very popular. The Idaho potato, high in starch content, is oval-shaped with brown skin and white flesh. Red Bliss potatoes are round with a low starch content.

Despite its reputation as a plebeian, dreary and fattening side dish, the potato is making a comeback, all in all, as a sumptuous main meal.