A recent study in the Annals of Internal Medicine debunked the long held belief among doctors that obese people underestimate the number of calories they consume. It turns out that the tendency to underestimate calories is proportional to the size of the meals we eat and, though larger people are more likely to eat larger meals (and thus more likely to think they've eaten less) we are all routinely eating larger portions without being fully aware of it.
Portions and food intake
Researchers have looked into how portions affect calorie intake. Here is some of what they've learned:
We tend to treat a portion of food as equivalent to a nutritional serving, taking cues from our surroundings in judging the appropriate size. In one study, University of Pennsylvania scientists left a large bowl of M&Ms at the front desk of an apartment building for 10 days with a sign encouraging people to help themselves, using the scoop supplied. On some days, the scoop held one-quarter cup, on others, 1 tablespoon. Passersby consistently took just one scoop, even though they were taking twice as much on some days as they did on others. This suggests we might be satisfied with smaller portions if only bigger ones weren't so easily available.
We've changed our view of which portion sizes are normal. In 2004, replicating a study first conducted in 1984, Rutgers University researchers asked college students to serve themselves typical portions of breakfast, lunch, and dinner foods from a buffet table. The students chose amounts that were not only bigger than the serving sizes on current nutritional labeling but also as much as 30% to 40% larger than those selected 20 years earlier.
Portion size can affect the amount we eat. In a Cornell University experiment, moviegoers who were served popcorn in containers holding a little over 8 cups ate 45% more than those served in containers holding half that amount. Even when the popcorn was two weeks old and recognizably stale, those using the large containers consumed 34% more. In a different study, Pennsylvania State University researchers manipulated the portions of baked ziti served as a main course at a restaurant. They used the regular portion on some days and one that was 50% larger on others. The price of the meal remained the same. Diners who were served the larger portion ate 43% more baked-ziti calories, as well as more of the accompaniments (a roll and butter and a stuffed tomato), yet surveys showed that all the customers thought their portions were equally appropriate.
Standard servings are generally much smaller than those dished out in restaurants or even at home. For example, according to the Food Guide Pyramid, a serving of pasta or rice is one-half cup - which doesn't look like much on a plate that can hold four to six servings. The Nutrition Facts label on packaged foods lists the number of servings in the container and the calories per serving. But we don't always read labels and may end up eating two or three servings' worth without being aware of it. What to do
Whether you eat out, prepare your own meals, or catch food on the run, portion control is essential to limiting your calorie intake. Here are some tips for keeping portions in proportion:
Train your eye. Measure out servings of the foods you commonly eat so you know what a single serving looks like. Developing an eye for serving sizes can be particularly helpful when dining out or attending social events, where portions may be too large or the food unlimited.
Change your tableware. Use a smaller bowl or a mug for cereal and a smaller plate at dinner; the amount of food will look more plentiful. Instead of using a fork, try chopsticks. They can make you eat more slowly, so that your stomach has a chance to register satiety and signal the brain that it's full.
Researchers at the University of Calgary in Canada tested specially designed portion control dishware in 130 obese patients with type 2 diabetes. Subjects were given attractive plates and bowls that were marked off in sections by food group and decorated with serving-sized food icons. The women's diet plate provided a 650-calorie meal. After six months, the dishware users had lost more weight and required less diabetes medication than a control group given usual care.
Eat a wide variety of whole foods. Although experts don't know the full story yet, they speculate that there are healthful synergistic effects among the many nutrients in a balanced diet. So eat a good mix of unprocessed foods - including whole grains, fruits, and vegetables (including legumes). Whole grains contain more vitamins, minerals, and fiber than refined grains. Fiber slows digestion and makes you feel full longer. The high water and fiber content of whole fruits and vegetables makes them a filling choice as well. Vegetables, fruits, and whole grains should take up at least two-thirds of your dinner plate.
Control portions at home. To discourage second helpings, serve food in the kitchen and take it to the table on plates. Try to eat at regular intervals throughout the day; if you wait until you're hungry, you're more likely to snack on the wrong kinds of food or overindulge at the next meal. Don't eat out of bags or boxes; put the correct amount in a bowl or cup or on a plate. Keep healthy snacks on hand in amounts of 100 calories or less - a banana or apple; one cup of blueberries, raspberries, or grapes; or raw vegetables with tomato salsa. If you crave an occasional sweet, cut up a candy bar and keep the pieces in the freezer; have only one "serving" at a time and let it slowly melt in your mouth.
Control portions while eating out. Go to restaurants that offer plenty of Ã la carte options; avoid buffets and salad bars. Instead of a dinner, order a low-fat appetizer and a large salad with dressing on the side. Ask to substitute fruits, vegetables, or a salad for French fries. Arrange with a dinner companion to split an entrÃ©e, or eat only half of the portion and take the rest home. At a cocktail party, instead of constantly grazing, allot yourself a few items, put them on a small plate, and don't take any more.
Borrow from mindfulness practices. Mindfulness means giving your full attention to the present. Try to bring all your senses to the experience of eating, including your surroundings. Take time to savor the texture, flavor, and aroma of your food. After taking a bite, put down your fork and chew slowly. These steps can help slow your eating and give your brain a chance to receive the message that your stomach is full. As author Leo Rosten observed, "Where there is too much, something is missing." What seems to be missing in our current era of supersized portions and expanding girths is a genuine enjoyment of high quality, nutritious food.
Dr. Suzanne Koven practices internal medicine with a special interest in weight issues at Massachusetts General Hospital in Boston, and teaches at Harvard Medical School.
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