Soup can do a lot more than warm you up — it can also fill you up and help you lose weight.

A recent study published in the journal "Physiology & Behavior" found that soups reduced hunger and increased fullness as much as solid foods. And total calorie intake was lower when participants ate soup rather than drinking similar quantities of ordinary beverages. "Soups have a water base, which keeps the calories down. They tend to make you feel more satisfied, so you eat less," says Barbara Rolls, professor of nutrition at Penn State University and author of the forthcoming book "The Volumetrics Eating Plan: Techniques and Recipes for Feeling Full on Fewer Calories." Dr. Rolls led the original groundbreaking research that found eating soup prior to your meal could reduce mealtime consumption by as many as 100 calories. However, "The soup itself must be fairly low in calories to be the most effective — otherwise you end up eating two meals," Rolls cautions.

Here are some tips to help you choose the right soup.

French onion vs. broccoli-cheddar soup

If you skip the added bread and cheese (which can add 350 calories), your best bet is French onion soup, made with sherry, onions, butter and beef bouillon, at about 100 to 200 calories per cup, depending on ingredients.

For instance, the Au Bon Pain chain's French onion has 80 calories per cup, whereas Panera Bread's has 220 calories per cup. And Applebee's French Onion Soup au Gratin has only 150 calories per cup, including a crouton and reduced-fat cheese.

On the other hand, broccoli-cheddar soup, often made with heavy cream, has about 175 to 275 calories per cup; Au Bon Pain's has 230 calories. Try to avoid cream and cheese soups in general.

Chicken noodle vs. chicken vegetable

While both are good choices, chicken vegetable is a bit lower in calories, on average, because it's missing the noodles. • Campbell's Kitchen Classics Chicken Noodle Soup (1 cup): 90 calories, 1g fat, 13g carbs, 6g protein, 870mg sodium

• Homemade chicken noodle soup, from scratch (1 cup): 300 calories, 7g fat, 28g carbs, 30g protein, 1,430mg sodium

• Campbell's Chunky Soup, Hearty Chicken with Vegetables (1 cup): 100 calories, 1.5g fat, 14g carbs, 7g protein, 790mg sodium

Black bean vs. lentil

This one's a close call. The only thing that really makes lentil a better choice is the sour cream (60 calories for 2 tablespoons) that's often served on top of the black bean soup .

Both of these legumes offer health benefits, including significant folate, magnesium, antioxidants, fiber and protein, with very low calories and fat. One additional benefit of black beans is the amount of iron, a nutrient many Americans tend to lack in their diets.

• Panera Bread's Low-Fat Vegetarian Black Bean Soup (1 cup): 160 calories, 1g fat, 31g carbs (11g fiber), 9g protein, 820mg sodium

• Goya Black Bean Soup (1 cup): 210 calories, 1.5g fat, 37g carbs (20g fiber), 11g protein, 1,050mg sodium

• Amy's Organic Lentil Soup (1 cup): 130 calories, 4g fat, 19g carbs (9g fiber), 8g protein, 590mg sodium

Minestrone vs. split-pea

Peas are an excellent source of fiber, folate and potassium, but split-pea soup is typically the loser calorie-wise. When the peas are pureed, they're sometimes combined with butter and cream, which boosts the calorie and fat content.

Minestrone, made with an assortment of vegetables and beans, ranges from 100 to 180 calories per cup and is consistently the better choice.

• Campbell's Kitchen Classics Minestrone Soup (1 cup): 110 calories, 0.5g fat, 22g carbs, 4g protein, 840mg sodium

• Progresso Green Split Pea Soup (1 cup): 170 calories, 3g fat, 25g carbs, 10g protein, 870 mg sodium

• Au Bon Pain's Split Pea with Ham (1 cup, but serving size is 12 ounces): 140 calories, 1g fat, 23 carbs, 10g protein, 680 mg sodium

Clam chowder vs. lobster bisque

You might think all clam chowders are equal, but the Manhattan version is tomato-based, whereas New England clam chowder is made with milk or cream, which makes it higher in calories and fat. But lobster bisque, typically made with heavy cream, can be the highest of all, coming in at 260 calories or more per cup — depending on the amount of butter, heavy cream and lobster used.

• Progresso Manhattan Clam Chowder (1 cup): 110 calories, 2g fat, 17g carbs, 6g protein, 880 mg sodium

• Campbell's Kitchen Classics New England Clam Chowder (1 cup): 240 calories, 16g fat, 20g carbs, 5g protein, 720 mg sodium

Hot and sour vs. egg drop vs. miso

All these soups are excellent choices. P.F. Chang's Hot and Sour Soup (made with chicken and bean curd) has only 56 calories per cup. Egg drop soup has only about 60 calories per cup, and traditional miso soup has only about 40 calories per cup.

Charles Platkin, nutrition and public health advocate, author and founder of Integrated Wellness Solutions. Copyright, 2005, by Charles Stuart Platkin. Write to info@thedietdetective.com