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The Portion Problem

Why do Americans find it so difficult to downsize at the dinner table?
WebMD Weight Loss Clinic-Feature
Reviewed by Louise Chang, MD

Although many Americans are aware that the portions we eat in restaurants and at home have grown larger and larger in the last few years, it seems few of us are actually doing anything to make up for it.

A recent national survey by the American Institute for Cancer Research (AICR) found that 45% of Americans are aware portion sizes have increased in restaurants, and 52% realize portion sizes have increased at home. Yet, for the most part, that didn't change their eating behavior. Only 25% of Americans say the portions they personally eat at restaurants have gotten smaller since 2003, and just 37% say they have cut back on portions at home.

When people were asked what determined how much they ate, nearly seven in 10 cited "the amount they were used to eating," according to the survey results. And the percentage of Americans who said they base the amount they eat on the amount they're served almost doubled in three years, from 30% in 2003 to 54% in 2006.

Why should we care about the size of our portions? Research suggests that people with more food in front of them tend to eat more, whether it's served to them on plates or they serve themselves from a container. In one study, researchers gave men and women different-sized submarine sandwiches (6, 8, 10, or 12 inches) once a week for four weeks. On days when they were served 12-inch subs, participants ended up eating more calories than on days they were served smaller subs.

Denial also seems to be a problem when it comes to serving sizes. A recent study found that people who were given large containers of popcorn at a movie theater ate more than those given medium-sized containers -- even when the popcorn was stale. When study participants were asked whether the big servings influenced how much they ate, the vast majority denied it had any effect.

At no other period in history have we faced the problem of too much food instead of too little, experts say. "And we are biologically ill-equipped to handle it," Marlene Schwartz, PhD, research director of the Rudd Center for Food Policy and Obesity, Yale University, says in an email interview.

So if we're aware of the portion problem, why can't we fix it? WebMD put the question to diet and nutrition experts.

The Clean Plate Habit

Experts agree that the "clean your plate, no matter what" habit is very powerful.

"We have performed studies that show that people tend to always put the same amounts on their plates even when plate sizes vary," David Levitsky, PhD, professor of nutrition and psychology at Cornell University, says in an email interview. "In part it is habit, a factor that is difficult to change."

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