August 2003

 

Watch Those Food Portions
Lynda Zimmerman, ZimmermanL@missouri.edu

The prevalence of overweight has increased dramatically in the U.S. since 1980, and research suggests a major reason why: Americans suffer from portion distortion. That is, we have become so used to super sized portions that we have forgotten what “normal” is.

Indeed, serving sizes of many restaurant and packaged foods have increased substantially during the past 20 years. New York University researchers Lisa R. Young and Marion Nestle compared usual portion sizes to federal standards and found that most portions exceeded standard sizes. In fact, portions of many foods and beverages were two to five times larger than when they were first commercially available. For example, a serving of French fries is now 5 ounces (525 calories) compared with 2 ounces (210 calories) in 1954; servings of soda, once 6 ounces (85 calories), are now 12 to 20 ounces (170 to 285 calories) or more.

But it’s not just restaurant meals that have gotten bigger. Researchers at the University of North Carolina at Chapel Hill analyzed data from three national surveys documenting portions of foods eaten by more than 60,000 Americans. “Between 1977 and 1996, food portion sizes increased both inside and outside the home for all categories except pizza,” wrote the study’s authors, Samara Joy Nielsen and Barry M. Popkin. Over the past 20 years:

• Hamburgers have expanded by 23 percent;
• A plate of Mexican food is 27 percent bigger;
• Soft drinks have increased in size by 52 percent;
• Snacks, whether potato chips, pretzels or crackers, are 60 percent larger.

Look around, and you will see other indicators of super sizing in our culture: dinner plates have grown from 10 inches in diameter to 12-1/2 inches; newer model cars have larger cup holders; “diet” foods and some brands of frozen dinners come in larger sizes. Some recipes have changed with the times, as well. In 1949, the Toll House chocolate chip cookie recipe listed a yield of 100 cookies per batch. Today, the exact same recipe has a yield of 60 cookies.

Do people eat more just because they are served more? You bet, says Brian Wansink, director of the Food and Brand Lab at the University of Illinois.

Wansink sent 79 parents home with a video and either one- or two-pound bags of M&Ms plus either a "medium" or "jumbo" movie-theater-sized tub of popcorn for each family member. On average, people ate 112 M&Ms from the one-pound bag and 156 from the two-pound bag. Likewise, the average person ate roughly half a tub of popcorn, whether it was medium or jumbo (which held twice as much). “People often eat about 50 percent more of snack-type foods like candy, chips, and popcorn when they come in bigger packages," says Wansink. "With other foods, the increase is usually about 25 percent."

Similar findings were reported by Pennsylvania State University investigator Barbara Rolls. She served different amounts of macaroni and cheese to 50 people each day for lunch to see if they would be influenced by the portion size. Allowed to eat as much as they wanted, the volunteers ate 30 percent more from a five-cup portion than from a serving one-half its size—an increase of 160 calories. "It didn't matter if it was men or women, dieters or non-dieters, people who were overweight or not, people who habitually clean their plates or not," Rolls said. "Everyone responded to the increased portion size by eating more."

The bottom line: It's not just what we eat but also how much we eat that matters. Larger portions can add 200 to 500 more calories over the course of a day—and 20 to 50 pounds in a year.

Sources: “Patterns and trends in food portion sizes, 1977-1998”, J Am Med Assoc, 289(4):450-453, 2003; “Foods commonly eaten in the United States, 1989-1991 and 1994-1996: Are portion sizes changing?”, J Am Diet Assoc, 103(1):41-47, 2003; “Portion size of food affects energy intake in normal weight and overweight men and women,” Am J Clin Nutr 76(6):1207-1213, 2002; “Can package size accelerate usage volume?”, J Marketing, 60:3 (July),1-14, 1996.