April 16, 2024 – Almost everyone who's watching their calories knows to bypass those family-size bags of snacks, with experts long warning us we’re likely to eat more than we planned.
Now, new research suggests that the size of the snack matters, too. Bottom line: To eat less, pick the smallest-size snacks.
In the study, 75 adults were given 2.5 servings of three sizes of pretzels during three visits and told to eat as much as they wanted. They ate the smaller pretzels more slowly, took smaller bites, and ate less overall than when they ate the medium and large pretzels.
There was one unexpected twist (and it wasn’t in the pretzel), said John E. Hayes, PhD, MS, a professor of food science at Penn State University in University Park , PA. While people ate less and more slowly when offered small pretzels, they had the highest intake of sodium with that size.
“The surface area is bigger, so when they sprinkle the salt on the outside, there is more sodium content per serving,” said Hayes, a study co-author.
The study results suggest that picking your snack size based on your goals is a good idea, according to lead study author Madeline Harper, a Penn State graduate student in food science.
“So, we’re suggesting that if you’re trying to watch your calorie intake or are trying to reduce the amount you are eating in a snack, then maybe a smaller pretzel would meet your needs better, because of the inherent way the size of the pretzel affects your eating rate," she said. But if your concern is limiting sodium (perhaps due to high blood pressure), the larger pretzel might be better because you’ll take in less sodium, she noted.
Study Specifics
During the study sessions, the researchers video recorded participants, noting how many minutes each person spent snacking, how many bites they took, and how much each ate in both weight and calories. The people in the study ate 31% more large pretzels than small and 22% more of the large pretzels than the medium ones. They ate the fastest and took the biggest bites when eating the large pretzels.
Small pretzels were .017 ounces each, medium .05 ounces, and large .35 ounces.
The researchers said the size of the pretzels alone did not affect how much a person ate, so that implies that the eating behaviors prompted by the different pretzel sizes were driving how much they ate. In short, the larger the pretzel size, the more quickly they ate, the bigger the bites, and the more they ate.
Hayes said his team was expecting that the eating rate would predict intake, as faster eating rates and larger bite sizes have been linked previously to eating more. Before the study, he wondered if those eating the small pretzels would grab a fistful. But that didn’t happen – they picked them up individually. “And we didn’t tell them how to eat,” he said.
One practical take-home, Hayes said, is that the research shows the speed at which people eat can be controlled, “and when we can slow people down, we can use that to help people eat less.” Several years ago, he said, British researchers studied eating rates in healthy-weight and overweight children, concluding that eating rate is a heritable characteristic, likely to be passed down from parents to children.
Expert Perspective
The findings of this study align with other research, said Evan Reister, PhD, a professor of health studies at American University who found in his recent study that people given large-size packages of snacks eat about 12% more than those given smaller snack packages.
Smaller snack sizes may prompt people to eat less for a few reasons, he said.
“People often assume that no matter the size of a snack, it can be consumed in one sitting. If it’s presented as a single unit [package], it’s easy for people to think that it should be consumed in a single sitting.” (Reister noted exceptions, saying he doesn’t expect anyone to eat a 5-pound candy bar at a single sitting.)
But if someone eats a “fun size” candy bar, for instance, “when they finish it, there is a period where they can pause and think about whether they want to eat another. If someone is eating a ‘share size’ candy bar, on the other hand, there is no pause period. This often results in eating more than perhaps you wanted to.”
