Research

Effects of portion size on chronic energy intake

Robert W Jeffery^{* 1} , Sarah Rydell^{* 1} , Caroline L Dunn^{* 1} , Lisa J Harnack^{* 1} , Allen S Levine^{* 2} , Paul R Pentel^{* 3} , Judith E Baxter^{* 1} and Ericka M Walsh^{* 1}

¹Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, MN 55454-1015, USA

²Department of Food Science and Nutrition, College of Human Ecology, College of Agriculture, Food and Environmental Sciences, University of Minnesota, MN 55454-1015, USA

³Hennepin County Medical Center and Department of Medicine, University of Minnesota, USA

author email corresponding author email* Contributed equally

International Journal of Behavioral Nutrition and Physical Activity 2007, 4:27doi:10.1186/1479-5868-4-27

Published:	27 June 2007

Abstract

Background

This study experimentally examined the effects of repeated exposure to different meal portion sizes on energy intake.

Methods

Nineteen employees of a county medical center were given free box lunches for two months, one month each of 1528 and 767 average kcal. Foods were identical in the two conditions, but differed in portion size. Meals averaged 44% calories from fat. Participants self-reported how much of each lunch was eaten. Unannounced 24-hour dietary recalls were also conducted by phone twice per week during each exposure period.

Results

Mean energy intake at the lunch meal was 332 kcal/day higher in large lunch than in small lunch periods (p < .001). Mean 24-hour energy intake was 278 kcal/day higher in large versus small lunch periods (p < .001). There was no evidence of compensation over time. Average weight change over the month of large and small lunches was 0.64 ± 1.16 kg and 0.06 ± 1.03 kg, respectively, about what would be expected with the observed differences in energy intake.

Conclusion

This study suggests that chronic exposure to large portion size meals can result in sustained increases in energy intake and may contribute to body weight increases over time.