Published in the Journal of the Academy of Nutrition and Dietetics, the research found that the volume of breakfast cereals could influence both the portions that people took and the amount they ate.
“As flake size was reduced, subjects poured a smaller volume of cereal, but still took a greater amount by weight and energy content,” the researchers wrote.
Consumers ate around 72 calories more when cereal flakes were smaller; a substantial 34% intake difference.
“Despite these differences, subjects estimated that they had taken a similar amount of calories of all versions of the cereal,” they added.
A group of 41 adults ate cereal for breakfast once a week for four weeks. The cereal had been crushed to reduce the volume to 80%, 60%, 40% or left as the standard flake size. The participants were provided with a constant weight of cereal in an opaque container and left to pour the cereal themselves; judging their own portions.
Thinking outside the cereal box
“Consuming 34% more calories at breakfast? That’s a big effect,” says Barbara Rolls, lead scientist
Speaking to BakeryandSnacks.com, lead scientist on the study Barbara Rolls said the study findings about the influence flake size had on consumption should be of significant interest to breakfast cereal manufacturers.
“Consuming 34% more calories at breakfast? That’s a big effect,” she said. “And this is related to something that hadn’t even really been thought about before, in terms of influencing intake. I think cereal manufacturers need to be aware that cereal flake size is an influence on how much people take and then how much they eat.”
Consumers pouring a compact granola, compared to a large volume cereal, could take up to two or three times more calories, she said.
Cereal manufacturers that wanted to develop healthier variants for the weight management category should consider enlarging cereal flake sizes, she said, but also reducing the calorie density of the product.
“Both those factors are important to look at. I think the focus has been on fiber and protein content and keeping sugar content down but an additional layer is looking at these physical properties and calorie density – it has a much more robust effect,” Rolls said.
As research into satiety and food consumption influences continued, she said these findings, “add information to the armoury of tools people have to use to attack the global over-consumption problem”.
Reducing density in cereal
However, reducing the density of dried foods such as cereal was not easy, she said.
“With cereal, keeping the fat and sugar content down are the main ways to reduce calorie density. Adding fiber can reduce it a bit, but you can’t add enough fiber to have a huge impact,” she explained.
However Rolls said that any formulation changes needed to keep taste at the forefront. “If the product doesn’t taste good, it’s not going to be a success.”
In addition, she said that any R&D work would have to consider cultural differences across countries, because, for example, cereal flake sizes and expectations differed from country to country.
Giving consumers a better idea of portion for each cereal
Rolls suggested that serving size should also be considered more carefully by manufacturers in light of the findings and adjusted according to the type, shape and size of the cereal. Because, for example, one cup of flaked cereal and one cup of granola differed hugely in portion size from a weight and calorie perspective.
She acknowledged that these adjustments could prove difficult, as flakes in the same box tended to differ in size, but said it was important because the volume of the cereal impacted the amount consumers take and consume.
“A number of cereals are pre-portioned, like oatmeal or Weetabix, but giving people some clue about what a portion is for other cereals would be quite helpful.”
Source: Journal of the Academy of Nutrition and Dietetics
Published online ahead of print, 19 March 2014. Doi: 10.1016/j.jand.2014.01.014
“Variations in Cereal Volume Affect the Amount Selected and Eaten for Breakfast”
Authors: BJ. Rolls, JS. Meengs and LS. Roe