It's no secret that Thanksgiving is among the least diet-friendly holidays on the calendar. Who can resist the savory aromas of casseroles and pies wafting from the kitchen, no matter how strong their dedication to fitness? Unfortunately, the foods of the season are often laden with butter, cream and sugar, all of which spell trouble if you're watching your waistline. But by avoiding the most fattening dishes on the table--or at least partaking in moderation--you can help spare yourself the post-feast guilt. Here are the worst offenders of Thanksgiving.

1. Sweet Potato Casserole

Those soft orange tubers laced with melting marshmallows have a healthy main ingredient--sweet potatoes are high in fiber and vitamin A, and very low in calories--but the butter, brown sugar and fluffy marshmallow topping make this indulgence one of the most fattening components of your dinner plate. Just one serving has about 460 calories, enough for a small meal. For a leaner version, go easy on the butter and sugar, and add just a few marshmallows.

2. Pecan Pie

Again, this dish starts with a relatively healthy base (pecans are nutritious, if naturally high in fat) and adds gobs of butter and sugar. Pair it with ice cream or whipped cream, and you're in even deeper diet trouble. If you can't resist the pie, lighten the calorie load by eating around the crust and avoiding toppings.

3. Stuffing

Stuffing packs a one-two punch of refined carbs from white bread and fat from butter. Some versions also include fatty sausage or other meats. To make a healthier stuffing, use vegetables such as onions and carrots instead of meat, ensure half of the breadcrumbs are whole wheat, and use just a pat of butter.

4. Mashed Potatoes and Gravy

Butter strikes again, and along with cream or milk, jacks up the fat content of an ordinary potato to artery-clogging levels. And who eats mashed potatoes without gravy? While the brown sauce may add juicy flavor to your spuds, it only adds more fat and calories. For a healthier side, use skim milk and just a touch of butter, and top your mashed potatoes with scallions and fat-free sour cream to enhance the taste.

5. Alcohol

OK, so it's not really a food. But calories from "adult beverages" can add up faster than you think. Each 4-ounce glass of red wine you put away with dinner has about 100 calories, and each regular beer has 140 calories. Sweet liqueurs like amaretto and Kahlua may wash down the meal nicely, but each shot of just 1.5 ounces has 165 calories. Mixed drinks are often the worst alcohol offenders of all--a 5-ounce serving of a margarita has a mind-blowing 550 calories. Where do they all fit in that tiny glass?

One last tip: drink plenty of water before and during your meal. The calorie-free beverage will fill you up so can't overindulge, and you won't even miss the extra calories.