Each of us is responsible for how much we eat, but research suggests that cultural and social norms can make it hard to choose appropriate portion sizes. Just in time for the holiday season, the November 2007 issue of Harvard Women’s Health Watch looks into how misperceptions about portions can affect calorie intake.

Harvard Women’s Health Watch notes that we tend to treat portions as equivalent to nutritional servings. A serving is a specific quantity of food designated on the basis of nutritional need. However, a portion—the amount you actually get on your plate, in the package, or at the counter—is often much bigger. We don’t always read the Nutrition Facts label, and may end up eating two or three servings’ worth. Studies suggest that we might be satisfied with smaller portions if bigger ones weren’t so easily available. Other research has shown that the more plentiful the food, the more we eat.

The Harvard Women’s Health Watch offers some tips for keeping portions in proportion:

Train your eye: Measure out servings (not portions) of the food you commonly eat so you know what a single serving looks like.

Change your tableware: Use a smaller bowl or a mug for cereal and a smaller plate at dinner.

Control portions at home: To discourage second helpings, serve food in the kitchen and take it to the table on plates.

Eat at regular intervals throughout the day: If you wait until you’re hungry, you’re more likely to overindulge at the next meal.

Control portions while eating out: Avoid buffets and salad bars. Instead of a dinner, order a low-fat appetizer and a large salad with dressing on the side.