WASHINGTON — Almost 70 percent of Americans have been overweight or obese in recent years, and more than 78 million people in the country have been counted as obese.
The problem has many sources, but one of them is obvious: increased portion sizes. We have a lot of evidence that people will eat whatever is put in front of them, even if they aren't hungry. As portion sizes expand, waistlines expand as well.
According to the Centers for Disease Control and Prevention, the average U.S. restaurant meal is more than five times larger than it was in the 1950s. The average hamburger, once less than 4 ounces, is now more than 12 ounces. The average order of French fries, once less than 3 ounces, is now more than 6 ounces. There is a clear correlation between increases in portion sizes and increases in obesity.
That correlation helps explain why obesity has been more prevalent in the United States than in France. The French eat high-calorie food, but their portion sizes are smaller. In supermarkets and restaurants, and in portion sizes recommended in cookbooks, Americans are given significantly bigger servings. Even at McDonald's, where we might expect identical sizes, servings of soda and French fries have been found to be larger in Philadelphia than in Paris.
Brian Wansink, a Cornell University professor of consumer behavior, helps to explain why portion sizes have such a large effect. He finds that much of our eating is mindless or automatic in that we tend to eat whatever is in front of us. If you are given a half-pound bag of M&M's, chances are that you will eat about half as much as you will if you are given a one- pound bag. People who receive large bowls of ice cream eat a lot more than those who get small bowls.