So you've gone the lean route, made yourself a sandwich with the lean turkey breast, the low-fat Swiss cheese and the reduced-fat bread. You're feeling pretty good about yourself.

Slideshow: Condiment Comparisons

Then you take that first bite. It's a bit dry. The flavor could use a little help. You add some lettuce and a slice of tomato, and it helps with the dryness but doesn't quite fix the flavor issue. You could add some salt, but that's not quite the complex flavor your palate's craving.

What you need is a condiment. Whether it's mustard, mayo, ketchup, relish, chow chow or any of the other couple-hundred options, you need a little something to bring some oomph to the party. The problem is, the wrong condiment can turn your healthy lunch into a fat-laden artery bomb waiting to hit your stomach like a wrecking ball -- and your waistline soon after.

Let's start off with the ultimate free add-on, good old yellow mustard. Did you know that one serving of yellow mustard, one teaspoon, has no calories, no fat, no carbs, no cholesterol and only 55 grams of sodium? Of course, if you go for a honey mustard or some of the sweeter options, you'll add some heft, but mustard in any form almost always gives you the biggest flavor bang per calorie of anything out there. If you're looking for the best, try Plochman's stone-ground mustard, or any similar product.

What's usually mentioned in the same breath as mustard? Mayonnaise, of course. People in the Southeast usually have a jar of Duke's, the greatest mayo on the planet, in the fridge. The stats for one of the major national brands, Hellmann's, are indicative of the entire category: 90 calories, 10 grams fat, 5 mg cholesterol and 90 mg sodium per tablespoon. If you try to go light by switching to a dressing like Miracle Whip, you're still getting 35 calories, 3 grams fat, 100 mg sodium and 2 grams carbs per tablespoon. That's less than half the calories and fat, but it still bears noting.

The serving sizes are problematic, too. Take a piece of bread and carefully measure out a tablespoon of mayonnaise. Spread it around. Is that anything like the amount you use? Probably not.

If you like the tanginess of dressing or the lemony zip of mayonnaise, you might want to give sweet relish a try. The texture makes is spreadable, and the flavor of even the national brands is quite good. Heinz sweet relish adds only 20 calories, 5 grams carbs and 95 mg sodium per tablespoon, with no fat or cholesterol. Just like mustard, you're talking about a big flavor impact per serving here.

While you're exploring the world of relish, check out some of your local creations. In the Deep South, for instance, you'll find a spicy concoction called chow chow that's good by itself or atop just about any sandwich not involving peanut butter.

We haven't yet mentioned the official condiment of childhood: ketchup. Whether your plate turned into the Great Red Smear or you were careful to keep your Heinz in a neat puddle, it's likely your younger years were fueled by ketchup.

Did you know that ketchup is, by definition, a sauce? It's actually used as an important flavoring component in a lot of South American and other ethnic recipes. Ingrid Hoffmann, host of "Simply Delicioso," surprised the Food Network folks by using it in several recipes and making it work.

In moderation, there's really not much wrong with ketchup. Heinz tomato ketchup provides 15 calories, 4 grams of carbs and 190 mg sodium per tablespoon serving. Once again, the key here is portion control. When's the last time you ate one serving of ketchup?

Next time you reach for the ketchup, though, think a bit farther south and grab some salsa. Talk about flavor per serving -- salsa comes in an incredible rainbow of flavors and heat levels. The "base model," Pace Chunky Salsa (medium heat), will hit you with just 10 calories, 240 mg sodium and 2 grams carbs per 2-tablespoon serving. You're getting fewer calories and half the carbs for double the serving size, with a small increase in sodium.

Salsa is the most popular condiment in the world. Keep it on hand!

And now, a couple of special instances:

Are you the type who reaches for the tartar sauce the minute anyone so much as mentions fish? If you're using good, fresh fish, slathering on the sauce is nearly criminal. With its 60 calories, 4.5 grams fat, 210 mg sodium and 4 grams carbs, that can turn even the leanest fish into a fat-laden party. Try squeezing some fresh lemon on the fish, or sprinkling on your favorite spice blend. Fish is meat, remember, and it will take seasonings like any other protein.

Are fish sticks on the menu tonight? You're already behind the caloric 8-ball. Don't make it worse. Try some malt vinegar, which adds 3 calories per tablespoon and nothing else. Pretend you're eating proper fish and chips.

Maybe it's steak night. Do you reach for your favorite steak sauce, like A-1? You'll be adding 15 calories, 3 carbs and a whopping 280 mg sodium per tablespoon to your meal. Reach for barbecue sauce, like KC Masterpiece, and you'll add 30 calories, 125 mg sodium and 7.5 grams carbs per tablespoon.

Instead, try one of the oldest condiments around, Worcestershire sauce. French's, one of the biggest American brands, gives you 2 calories, 150 mg sodium and 3 carbs per serving. Best of all, it penetrates the meat better and, again, delivers far more flavor per serving than the others.

Make your choices wisely and you can keep that healthy meal or sandwich healthy!