Although the research wasn't specifically looking at
people who were trying to lose weight, it "indicates that
single-serving packages may help overweight individuals," author
Hollie A. Raynor told Reuters Health by email.
Raynor, a researcher in the Department of Nutrition at the
University of Tennessee in Knoxville, wanted to know if
single-serving packaging offers cues about the appropriate amount to
She and a colleague recruited people around the university and 64
ended up seeing the study through to the end. Some were overweight
and some were healthy weight, and some were watching their food
intake while others were not.
Half the participants received a box of 20 single-serving packs of
pretzels, each just under one ounce. The rest received two
standard-size bags of pretzels, each 10 ounces.
Researchers told everyone to take the pretzel bags home for four
days, eating as much or as little as they preferred, then return
them. Participants were also asked to fill out a form detailing when
and where they ate the pretzels.
The researchers estimated how much each person had eaten by weighing
the pretzel bags returned to them on day four.
On average, people in the healthy weight group ate about 135 grams
of pretzel, compared to 155 grams for the overweight group.
Of those who got bigger bags of pretzels, the healthy weight group
ate an average of 112 grams, compared to 204 grams in the overweight
But among those who had the single serving packs, the overweight
group actually ate less than the healthy weight group, 107 grams
compared to 158 grams.
The results were published in the Journal of the Academy of
Nutrition and Dietetics.
It is interesting that fat and thin people seemed to differ in
opposite directions in this study, said David A. Booth, a professor
of psychology at the University of Birmingham in Edgbaston, U.K.
But it's hard to generalize these results for people who are trying
to lose weight, he told Reuters Health in an email.
"Only two extreme conditions were contrasted: one packet was 11
times bigger than the other," he said. "Where does the effect cut
It will be more useful once we have comparisons of packages of more
similar sizes, he said. And it may not be that overweight people
react more strongly to packaging cues, he added — it could be they
are more dissuaded by the extra effort of opening lots of little
packages than are healthy weight people.
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Laurits Rohden Skov, who studies public health and nutrition at
Aalborg University in Copenhagen, Denmark, recommended taking these
results "with a pinch of salt."
The study was quite small and the wide variation in consumed
pretzels might have been due to many things, he said.
He was not involved in the study, but he thinks it is an important
area of research.
"One of the major determinants of modern obesity is
overconsumption of calories, and ecological research has shown a
link between increasing portion sizes and increasing prevalence of
obesity," Skov told Reuters Health.
"People do not eat a reflective and conscious amount of grams when
they eat, they eat units, and one unit of pretzels is for many
people one bag of pretzels," he said. "Likewise, people finish what
they have on their plate, because the plate is perceived as one
He doesn't think overweight people are more susceptible to
packaging cues, but that smaller package sizes can help people with
For both groups, those who were watching what they ate consumed
slightly less than those who were not dieting, but not enough to
make a statistical difference, the study authors report in the
Journal of the Academy of Nutrition and Dietetics.
"I believe the valid and sensible conclusion we can draw is that
packaging can indeed affect intake in overweight or obese people,"
France Bellisle, a researcher in the Nutritional Epidemiology Unit
at Universite Paris 13 in Bobigny, France, said.
But it is difficult to take much from this study because each group
of participants was so small, she said.
Single-serve packets tend to be more expensive than bulk packaging,
but there are other ways to try to keep your serving sizes down,
"If someone feels this is a helpful option for them, they can make
their own single-serving packages with baggies," she said.
Journal of the Academy of Nutrition and Dietetics, online February
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