By The American Institute for Cancer Research

The obesity epidemic is one of the most serious health problems facing America. If you’re overweight, you have an increased risk for chronic diseases, like diabetes, heart disease and cancer. Approximately 14 percent of cancer deaths among men and 20 percent among women are related to excess weight.

The growth in food portions has long been considered one reason for the rising number of obese and overweight people. In 1955, a single order of French fries weighed 2.4 ounces. Today, an average single serving is 7.1 ounces – nearly a 200 percent increase. Portions of other foods, like pasta, soft drinks, cereal, beer and coffee, have also increased dramatically in the last five years.

But until three years ago, health experts could only make educated guesses that portion size influenced weight gain. For example, in 1999 the American Institute for Cancer Research (AICR) compared the size of American bagels, croissants and quesadillas to their native counterparts in Poland, France and Mexico. Alarmed, AICR pointed out that the American versions had ballooned in size, weight and calorie content.

Bigger Portions Do Cause Overeating

But now research results are rolling in. Bigger portion sizes have been shown to encourage overeating by as much as 56 percent.

In one study, volunteers were served different-size submarine sandwiches on four different days: 6-inch, 8-inch, 10-inch and 12-inch. When served the 12-inch sandwich compared to the 6-inch, women ate 31 percent more calories and men ate 56 percent more. People ate more because they had more to eat, not because they were hungrier.

Another study showed that a larger than usual snack doesn’t prompt people to cut back later. When volunteers were served a larger bag of potato chips as an afternoon snack, women ate 18 percent more calories and men ate 37 percent more. When dinner was served several hours later, both women and men ate their usual amount.

Downsize Your Servings

To control your portion size and prevent overeating, first recognize you should eat only as much as your activity levels require. To do this, it may help to see how your regular portions compare to USDA standard servings.

Pour out your regular portion of hot cereal into a bowl. Into another bowl, pour one-half cup. That is the USDA standard serving. Compare the two. If you jog four miles a day, you might need all the energy your regular portion supplies. But if you seldom exercise and are putting on weight, you should consider cutting back little by little. A list of USDA serving sizes can be found online at www.aicr.org/publications/nap/napaids.lasso.

To control portion sizes at restaurants, order half-sizes or the smallest size, or share an entrée. Another option is to place half of your meal into a doggie bag before you start eating and take it home.