What you can do

Look for the number of servings per container, and if you plan to eat the entire contents, do the math. To limit portions, take these steps:

Use small dishes

People tend to fill up whatever dish they're using, then judge that amount as appropriate. And research shows that people think they're getting more food when it's served on a small plate than when it's on a big one. You can join Wansink's Small Plate Challenge (www.smallplatemovement.org) and pledge to eat your largest meal of the day off a 10-inch plate for a month to see whether it curbs your calorie intake.

Savor meals

Finishing your meal in less than 20 to 30 minutes might lead to overeating and make you feel too full.

Don't eat from the bag or box

"When you eat out of a package, you're likely to keep eating until it's all gone—no matter how many servings the package actually contains," says Marisa Moore, a registered dietitian and national spokeswoman for the American Dietetic Association. Instead, pour one serving into a small bowl or split a container into single-serving packs that you can grab for a quick snack.

Choose your glass wisely

Studies have found that people underestimate how much they've poured into a short, wide glass. Use a tall, slender glass for alcohol and other high-calorie beverages.