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Research and Professional Brief
The Accuracy of Stated Energy Contents of Reduced-Energy, Commercially Prepared Foods

https://doi.org/10.1016/j.jada.2009.10.003Get rights and content

Abstract

The accuracy of stated energy contents of reduced-energy restaurant foods and frozen meals purchased from supermarkets was evaluated. Measured energy values of 29 quick-serve and sit-down restaurant foods averaged 18% more than stated values, and measured energy values of 10 frozen meals purchased from supermarkets averaged 8% more than originally stated. These differences substantially exceeded laboratory measurement error but did not achieve statistical significance due to considerable variability in the degree of underreporting. Some individual restaurant items contained up to 200% of stated values and, in addition, free side dishes increased provided energy to an average of 245% of stated values for the entrees they accompanied. These findings suggest that stated energy contents of reduced-energy meals obtained from restaurants and supermarkets are not consistently accurate, and in this study averaged more than measured values, especially when free side dishes were taken into account. If widespread, this phenomenon could hamper efforts to self-monitor energy intake to control weight, and could also reduce the potential benefit of recent policy initiatives to disseminate information on food energy content at the point of purchase.

Section snippets

Methods

This study involved measurement of the energy content of 39 commercially prepared restaurant foods and supermarket frozen convenience meals obtained in the Boston, MA, area, and comparison of measured values with nutrition information stated by the vendor or manufacturer. The restaurant chains included in the study were selected as a convenience sample of quick-serve and sit-down restaurant chains with broad distribution throughout the United States who provided information on nutrient contents

Statistical Methods

Although formal statistical methods do not apply to convenience samples, standard statistical tests were employed to summarize the data for exploratory purposes and to suggest directions for future study. Differences in energy content (measured vs stated) were therefore compared by using two-sided t tests of whether the observed mean was within sampling variability of zero. Multifactor analysis of variance was used to examine potential predictors of the percent difference between stated and

Results and Discussion

The energy contents of individual foods are given in the Table, and Figure 1 illustrates percent differences between measured and stated values. On average, restaurant foods contained 18% more energy than stated; however, there was substantial variability in the difference between measured and stated values, and some foods contained twice as much energy as stated. The measured energy content of supermarket-purchased meals was also greater than stated values, by 8%. There was no statistically

Conclusions

Mean measured energy contents of reduced-energy restaurant and supermarket meals in this pilot study exceeded vendor-stated amounts by substantially more than could be accounted for by laboratory measurement error. Although the discrepancies were within acceptable limits based on federal regulations for most packaged and restaurant foods (which are not subject to these federal regulations) some restaurant foods did have measured energy contents that were double those stated by the restaurant,

L. E. Urban is a doctoral degree student, Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA.

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    L. E. Urban is a doctoral degree student, Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA.

    E. Saltzman is chair, Department of Nutritional Sciences, Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA.

    L. M. Ausman is Saqr bin Mohammed Al Qasimi Professor in International Nutrition, Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA.

    G. E. Dallal is director, Biostatistics Unit, Energy Metabolism Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA.

    L. M. Robinson is a research dietitian, Energy Metabolism Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA.

    S. B. Roberts is director, Energy Metabolism Laboratory, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA.

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