Finishing Off the Bigger Plate

Food consumption up when given bigger portions despite knowing about portion sizes

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) Though the pen is mightier than the sword, knowledge is not mightier than the fork, especially when there's a lot of food on the plate.

Even after learning about portion sizes and how they impact food consumption, people given large servings of food still ate more than those given smaller servings, a recently published study found.

The results demonstrated the need to find different ways to reduce portion size and how it affects overeating, according to the researchers.

"Check your serving size."

Karen Cavanagh, MS, and Lenny Vartanian, PhD, from the University of New South Wales in Australia, led an investigation into whether the amount of food consumed would be affected by a brief education and mindfulness exercise regarding portion sizes.

The study included 96 college women who were enrolled in a first-year psychology course and given credit for participating in the study.

Participants were assigned to one of two portion size conditions and one of three information conditions.

Half the participants were served a small (350 grams) portion of macaroni pasta with tomato sauce for lunch. The rest received the large (600 grams) portion of pasta.

Both groups could eat as much as they wanted and were provided with additional pasta to ensure they had equal quantities of up to 1,100 grams.

The three information conditions consisted of education, mindfulness or a simple brochure about sleep hygiene unrelated to food.

The education condition discussed different internal and external influences on behavior in general, eating behavior and the importance of being aware of the influences.

Participants in the education group wrote about any outside influences on their food intake, including social influences, advertising and portion size.

Those in the mindfulness group learned about influences on food intake, overeating consequences, mindless eating and tips for eating mindfully.

Researchers found that the size of the food portion significantly affected how much food was consumed. Neither of the educational activities reduced the effects of portion size.

Those who were given the smaller portion ate less than those given the larger portion. The larger portion group consumed an extra 87 calories compared to the smaller portion group on average.

"The brief education and mindfulness exercises used in the present study were not effective in reducing the portion size effect, although there was a tendency for participants who completed the mindfulness exercise to eat less overall," researchers wrote in their report.

Future research should look into ways to reduce the effect of portion size on excessive eating as well as how mindfulness can be used to reduce excessive eating.

The authors noted that the study did not occur in a real environment, but that previous studies had investigated similar feats in home, restaurant and other settings.

In addition, only female university students were included in the study.

The study was published in the May issue of the Journal of Health Psychology. The Discovery Projects by the Australian Research Council funded the study.

Reviewed by: 
Review Date: 
April 20, 2013
Last Updated:
August 14, 2013