May 14, 2004 -- Heard of the "see-food diet?" In fact, visual aspects of food -- not just willpower -- figure into how much we eat, a new study shows. It's why, at potlucks and buffet lines, our weight-loss plans go out the window.
Face it; a buffet table can lure us into eating more than normal. Really, that's what research has shown. The visual aspect of it all -- how food is displayed and the variety of colors -- is the subject of a new study appearing in the Journal of Consumer Research.
These little-understood cues can lead people to overindulge (and forget weight loss) without realizing why they are, writes researcher Barbara E. Kahn, PhD, with the University of Pennsylvania.
"Indeed, unless one is physically stuffed with food, he or she can always make room for more," she writes. "While physiological factors (such as hunger) can account for some differences in consumption, it is becoming increasingly evident that environmental contextual cues can also influence consumption."
Food packaging, shape, volume -- they all contribute to how much we eat, she explains. Variety also plays a big role. If we're given three flavors of yogurt to eat, we'll eat 23% more yogurt than if given one flavor, research has shown.
Because of it, we're a nation of overweight people trying to figure out a magic weight-loss secret.
Jelly Beans, M&Ms, and You
To further investigate how variety affects food intake, Kahn and her colleague conducted six experiments. Among them:
The jelly bean experiment: The 91 adults in this study were offered jelly beans as a thank you for participating in a PTA project. Each was randomly offered four different assortments of jelly beans -- composed of six, colored flavors.
When the six flavors were organized in bowls, either as single-flavored jelly beans or combined. The researchers found that the parents tended to eat more of the jelly beans as the variety of the jelly beans increase in the bowls.
The M&M experiment: A group of 105 adults were given 16-ounce bowls of M&Ms to eat while watching a television pilot show. They were told to eat as many as they wanted. Some bowls contained 10 different colors of M&Ms; some bowls had seven colors. The participants that had M&M bowls with 10-colors ate more M&Ms than the group that had bowls that contained only seven colors of M&Ms.
All six experiments showed researchers that not just variety -- but the perception of variety -- affects how much we eat.
The Eyes Are Tricksters
"People eat with their eyes, and their eyes trick their stomachs," co-researcher Brian Wansink, PhD, with the University of Illinois at Urbana-Champaign. "If we think there's more variety in a candy dish or on a buffet table, we will eat more. The more colors we see, the more we eat," he says in a news release.
In a previous study, Wansink found that moviegoers given an extra-large bucket of popcorn will eat up to 50% more than if given a smaller container -- even if the popcorn is stale.
Office employees will eat more if food is nearby, if a package is open, or if a container is clear rather than opaque.
"Many of us are reasonably diligent about what we eat, but we don't put that much thought into how much we eat," says Wansink. "People may decide to eat grapes instead of potato chips because it's healthier. Once they make that initial choice, they tend not to monitor how much they eat. And a pound of grapes isn't calorie-free."
Eating 100 fewer calories in a day might help us lose 10 pounds by year's end -- rather than gaining that much weight, he explains. "Small factors, like the type of candy bowl in your office, might add five more Hershey's kisses a day to your diet." That's 125 calories a day -- but it adds up over time.
If weight loss is the goal:
- At buffets and potlucks, keep no more than two foods on your plate at one time.
- If you're setting up a buffet line, give dieters a break: Don't put out multiple bowls of the same food.
- Don't cram buffet tables with too many different items.
- Arrange fruits and vegetables in less-organized patterns -- to stimulate appetites.