A marketing trick notorious for its ability to prompt children to eat more food than is healthy fails to work at the opposite end of the age spectrum, research shows.
Plenty of existing studies link food consumption with the size of the portion presented.
As early as 2003 a study in the American Journal of Clinical Nutrition found that doubling the portion size of an entrée caused kids to eat more of it, increasing their total energy intake by as much as 25%.
Large portion sizes, the researchers concluded, “may constitute an ‘obsegenic’ environmental influence for preschool-aged children by producing excessive intake at meals”.
The same trick also works with adults. A 2005 study enlisted 158 movie-goers in Philadelphia and randomly assigned them popcorn in either 120 or 240 gram containers. The food was further divided into fresh and stale samples.
The researchers found that people given fresh popcorn in a big container ate 45% more of the stuff than those with smaller fresh portions. Even those faced with 14-day-old popcorn – which must have tasted like corrugated cardboard – ate 33% more from big containers than small ones.
Age, however, it seems, brings wisdom. In a study published in the journal Appetite, researchers led by Michelle Eykelenboom from the Amsterdam Public Health Research Institute in The Netherlands set out to see if portion size influenced consumption in older people.
The researchers enlisted a cohort of 205 people, most aged over 65, with the eldest well into their eighties. The participants were randomly assigned either a 350 or 1000 gram jar of peanut butter and told to spread some on a slice of bread.
The results showed that those with the small jars used an average of 12.4 grams of the stuff, while those with the big ones deployed on average 12.6 grams – a negligible difference. The results held regardless of whether the participants were standard weight, overweight or obese.
“Increased package size has no effect on usage volume of peanut butter among older adults,” the authors concluded, with admirable precision.
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