Big Portions, Big Calories, Big Weight Issue

Oct. 19, 2005 -- Your eyes may lead you astray when you're watching your weight.

It's tough to resist a plate piled high with delicious food, and even itty-bitty bags of chips and cookies can be awfully tempting, new research shows.

That can't-put-the-fork-down tendency may start at a tender age, obesity experts told the annual scientific meeting of the North American Association for the Study of Obesity (NAASO).

Portion size was a hot topic at NAASO's meeting, held in Vancouver, Canada. Here are the findings of three serving-size studies presented at the meeting.

The bottom line: If it's on your plate or in your pantry, you're probably going to eat it. Be advised the next time you encounter your favorite food temptations.

Amount Counts

Let's say you like potato chips. Would you munch less if you had a bunch of little bags of chips rather than one king-sized package?

Don't count on it, advises Hollie Raynor, PhD, RD. She's an assistant professor of research at Brown University's medical school.

"Consumers might think they will eat less by purchasing pre-packaged quantities of individually sized snacks rather than one bigger bag or box. However, our study suggests this is not the case," says Raynor in a news release.

Snack Study

Raynor and colleagues gave the same amount of snack food to 28 healthy nonobese college students who regularly ate snacks and weren't trying to lose weight.

The snacks -- potato chips, cheese crackers, cookies, and candy -- were split into one big box or four little boxes. Calories and amounts of food were the same.

One group of students got a big box of snacks totaling 4,350 calories. Another group got the same amount of food, also with 4,350 calories, divided into four little boxes. Ditto for package sets with 8,750 calories each.

The rules: Eat as much as you want of the packaged snacks, don't eat other snacks, and return any leftovers after three days.

Snacking Without Limits

The students all ate about 60% of the snack foods they received, no matter how it was packaged.

That means that the students who got the little boxes probably plowed through more than one box.

When more snacks were on hand (the 8,750-calorie snack sets), the students ate 81% more calories.

"This suggests that the smaller portions did not influence intake, but that the amount of food provided suggested an appropriate amount to eat," write the researchers.

Can't Say No

Portion size mattered in the second study.

Researchers supplied all food and drinks to 23 adults. For 11 days, they used standard-sized servings. For another 11 days, they used portions that were 50% bigger.

The schedules were randomly assigned, with a two-week break in the middle of the study.