The study, accepted for publication in the International Journal of Obesity, examined the food choices and perceptions of 186 participants presented with pairs of coleslaw, cereals and drinks – either ‘standard’ or carrying nutrition claims likely to be interpreted as healthier, such as ‘reduced fat’. The ‘healthier’ varieties actually contained the same calories per 100 g as the ‘standard’ varieties.
For each food, the participants served themselves what they considered to be an appropriate portion, and estimated the energy density. In addition, they rated how guilty they would feel about eating the food, on a scale of 1 (not at all guilty) to 5 (very guilty).
The food pairs were reduced fat and luxury coleslaw; semi-skimmed milk and Sprite; and Frosties and Special K cereals.
The researchers found that participants consistently rated the ‘healthier’ choices as lower in energy than the ‘standard’ choices. They also served themselves portions that were 28% (semi-skimmed milk) to 71% (reduced fat coleslaw) larger than recommended serving sizes for five out of the six foods. Only Sprite’s portion size was estimated in line with the recommended serving size.
Principal researcher at the University of Ulster, Professor Barbara Livingstone, said: “This study supports what is described by many as ‘the health halo’ effect; that is, that consumers perceive these products to be healthier and with less calories than the ‘standard’ version food. They see them as representing the less guilty option and so eat more of them. Further education on what is a healthy portion size is warranted to overcome these misconceptions.”
The study found that the ‘reduced fat’ designation was most likely to be associated with an underestimate of calories, as well as an overestimate of appropriate portion sizes.
“Unbeknownst to the consumer, the reduced fat is often compensated for by other ingredients such as sugar to maintain the taste and textural properties,” the researchers wrote. “In fact, the consumption of low fat foods is often associated with a higher intake of carbohydrates and sugar, along with a higher overall energy intake.”
Source: International Journal of Obesity
Accepted article preview: doi:10.1038/ijo.2013.69
"Perceived 'healthiness' of foods can influence consumers' estimations of energy density and portion size"
Authors: G P Faulkner, L K Pourshahidi, J M W Wallace, M A Kerr, TA McCaffrey, M B E Livingstone